STATE  GEOLOGICAL  SURVEY. 

Governor  C.  S.  Deneen,  T.  C.  Chamberlin,  E.  J.  James,  Commissioners; 
H.  Foster  Bain,  Director. 


Contributions 

TO  THE 

Stratigraphy  of  Illinois 


The  Salem  Lime^one 

■ i I-  ^ f k ^ 

BY  . 

STUART  WELLER 


Lower  Paleozoic  Stratigraphy  of  Southwe^ern 

Illinois 

BY 

T.  E.  SAVAGE 


Notes  on  Shoal  Creek  Lime^one 

BY 

JON  UDDEN 


[From  Bulletin  No.  8.  Yearbook  for  1907.] 

URBANA 
University  of  Illinois. 

1908 


557 

J — \ 'pj 


THE  SALEM  LIMESTONE. 

(By  Stuabt  Weller.) 


Contents. 


Introduction  

Relationship  to  the  Warsaw  formation 'of  Hall 

Relationship  to  the  St.  Louis  limestone  

The  Meramec  group  of  Ulrich 

Geographic  distribution  in  Illinois  ^ 

Hancock  county 

St.  Clair  county, 


Monroe  county . 
Jackson  county. 
Union  county . . . 


Conclusion  . , . 


Appendix  


RagR 

82 

83 

88 

90 

90 

90 

90 

91 

93 

94 
97 

97 

98 
98 


P 


37 


^99 


8i 


—6  G.  S 


82 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


Introduction. 

The  '‘Bedford  limestone”  of  Indiana  is  one  of  the  best  known  and 
most  widely  used  building  stones  in  the  United  States  at  the  present 
time.  The  distribution  of  this  limestone  in  Indiana  has  been  shown 
by  Hopkins  and  Siebenthal,*  in  the  reports  of  the  Geological  Survey 
of  that  state,  and  the  same  authors  have  described  the  occurrence 
and  characteristics  of  the  stone,  and  the  methods  of  conducting  the 
quarrying  operations.  In  their  report  these  authors  have  used  the 
trade  name  “Bedford”  as  the  name  of  the  entire  formation  which  is 
called  the  Bedford  limestone,  but  this  useage  is  apparently  ill-advised 
because  of  the  prior  use  of  the  name  Bedford  for  a formation  in  Ohio 
at  the  base  of  the  Mississippian.f  Cumings  has  proposed  the  name 
Salem  limestone^  as  a substitute  for  the  Bedford  limestone  of  Hop- 
kins and  Siebenthal,  and  that  name  is  adopted  in  the  present  paper. 
Ulrich  has  rejected  both  the  names  Bedford  and  Salem,  and  uses  the 
name  Spergen  limestone§  for  the  formation,  but  the  substitution  of 
Spergen  for  Salem  seems  to  be  wholly  unwarranted. 

The  fauna  of  the  Salem  limestone  has  long  been  a notable  one  in 
the  literature  of  American  paleontology,  because  of  the  remarkable 
condition  of  preservation  of  the  fossils  in  certain  of  the  Indiana  locali- 
ties, and  because  of  the  great  numbers  of  individuals.  The  fauna  was 
first  described  by  Hall,  chiefly  from  material  collected  at  Spergen  Hill 
and  Bloomington,  Indiana,  ||  but  without  illustrations,  the  beds  furnish- 
ing the  fossils  being  referred  to  the  Warsaw  limestone  of  the  Missis- 
sippi river  section.  At  a later  date  Whitfieldlf  republished  Hall’s  orig- 
inal descriptions  of  these  Indiana  fossils  with  additional  notes,  accom- 
panied by  illustrations  drawn  from  the  original  type  specimens.  Still 
later  Hall  republished  his  original  paper  with  additional  notes,  accom- 
panying the  paper  by  the  same  plates  of  illustrations  which  were  pub- 
lished by  Whitfield.**  These  three  papers  gave  to  this  fauna  such 
notoriety  that  it  has  been  commonly  spoken  of  as  the  Spergen  Hill 
fauna,  and  had  not  Cumings  previously  used  the  name  Salem,  Ulrich’s 
name,  Spergen  limestone,  would  have  been  highly  appropriate  as  a 
name  for  the  formation. 


•The  Bedford  Oolitic  Limestone,  by  T.  C.  Hopkins  and  C.  E.  Siehenthal.  21st  Ann.  Rep 
Ind.  State  Geol.  pp.  289-427  (1896). 

tFor  a discussion  of  the  usage  of  the  name  Bedford  see  remarks  by  Cumings,  Siebenthal, 
Chamberlin  and  Prosser,  Jour-,  Geol.,  vol,  9,  pp.  232-235.  267-271;  also  Revised  Nomenclature  of 
the  Ohio  Geological  Formations,  by  Charles  S.  Prosser,  Geol.  Surv.  Ohio,  4th  ser..  Bull.  No. 
7,  pp.  19-20. 

fjour.  Geol.,  vol.  9,  p.  233,  (1901.) 

§The  Lead  Zinc  and  Fluorspar  Deposits  of  Western  Kentucky,  by  E.  O.  Ulrich  and  W.  S. 
Tangier  Smith,  U.  S.  G.  S..  Prof.  Pap.,  No.  36,  pp.  28-30,  (1905.) 

I]  Trans.  Albany  Inst,  vol.  4,  pp.  2-36  (1856). 

if  Bull.  Am.  Mus.  Nat  Hist,  vol.  1,  pp.  39-97,  plates  6-9  (1882). 

**12th  Ann.  Rep.  Ind.  State  Geol.,  pp.  319-375,  plates  29-32  (1883). 


Weller.] 


THE  SALEM  LIMESTONE. 


83 


A peculiar  feature  of  the  Spergen  Hill  fauna  as  it  was  described  by 
Hall  and  by  Whitfield,  is  the  diminutive  form  of  most  of  the  species, 
but  further  investigation  of  the  fauna  in  other  localities  has  shown 
that  many  of  them  often  attain  larger  and  more  nearly  normal  propor- 
tions, and  that  many  of  the  forms  have  a wide  geographic  distribu- 
tion. In  connection  with  these  later  investigations,  many  additional 
species  have  been  recognized  in  the  fauna,  which  have  been  described 
by  various  authors  in  various  places,  and  have  usually  been  recorded 
as  from  either  the  Warsaw  or  the  St.  Louis  limestone.  The  latest 
contribution  to  our  knowledge  of  this  fauna  is  a paper  entitled  “The 
Fauna  of  the  Salem  Limestone  of  Indiana,”*  which  has  been  contrib- 
uted to  by  E.  R.  Cumings,  J.  W.  Beede,  E.  B.  Branson  and  E.  A. 
Smith.  In  this  paper  an  attempt  has  been  made  to  gather  together  in 
one  place,  all  information  available  concerning  the  fauna  as  it  occurs 
in  Indiana. 

In  the  present  paper  the  occurrence  of  this  formation  in  Illinois  will 
be  discussed.  Its  relations  to  the  other  formations  of  the  Mississippian 
series  will  be  considered,  as  well  as  its  general  physical  characters, 
its  geographic  distribution,  and  its  possible  utilization  as  a building 
stone.  No  attempt  will  be  made  to  describe  in  detail  the  fauna  as  it 
occurs  in  Illinois,  but  as  complete  lists  of  species  as  can  be  made  at 
the  present  time,  will  be  given  in  an  appendix,  for  the  various  localities 
from  which  fossils  have  been  collected. 


Relation  of  the  Salem  Limestone  to  the  Warsaw  Formation  . 

OF  Hall. 

It  has  long  been  recognized  that  certain  limestone  beds  in  Illinois 
contain  representatives  of  the  Spergen  Hill  fauna  of  Indiana,  indeed, 
one  locality  above  Alton  was  frequently  mentioned  by  Hall  in  his 
record  of  the  geographic  distribution  of  the  species  in  the  original 
description  of  the  fauna.  This  locality  was  referred  by  Hall  to  the 
Warsaw  limestone  formation,  as  were  also  the  beds  in  Indiana  bearing 
the  Spergen  Hill  fauna. 

The  typical  section  of  the  Warsaw  limestone,  at  Warsaw,  Hancock 
county,  Illinois,  as  given  by  Hall,  is  as  follows:! 

Feet. 

3.  Coarse  calcareous  yellow  sandstone,  in  thick  heavy  beds,  quarried  for 
building. 

2.  Argillaceous  limestone  with  shaly  partings,  containing  abundance  of 

large  Archimedes  and  other  bryozoa;  thickness  at  Warsaw 25 

1.  Magnesian  limestone  of  variable  thickness,  and  sometimes  absent. 

Worthen  did  not  recognize  the  Warsaw  limestone  as  a distinct  major 
division  of  the  Mississippian  in  Illinois,  but  included  all  the  beds  so 
designated  by  Hall  in  the  “St.  Louis  Group,”  extending  this  interpre- 
tation to  the  limestone  beds  above  Alton  and  to  those  at  Spergen  Hill 


* 3\)th  Ann.  Rep.  Ind.  State  Geol.,  pp.  1187-1486,  plates  7-47  (1906). 
t Geol.  Surv.,  Iowa,  vol.  1,  pt.  1,  p.  161. 


84 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


and  Bloomington,  Indiana.*  In  his  report  on  Hancock  county, 
Worthen  has  as  usual  considered  the  beds  comprising  the  typical 
Warsaw  formation  of  Hall  as  a part  of  the  St.  Louis  lirriestone  and 
has  given  the  following  section  of  the  beds  as  exposed  at  the  typical 
locality,  f 

Feet. 


4.  Concretionary  and  brecciated  limestone 10-30 

3.  Calcareous  grit  stone 10 

2.  Blue  shales  and  Archimedes  limestone 20 

1.  Magnesian  limestone: 8-12 


The  beds  i,  2 and  3 in  Worthen’s  section  are  identical  with  those 
given  the  same  numbers  in  Halhs  section ; No.  4 of  Worthen’s  section 
being  the  only  bed  at  this  point  included  in  the  St.  Louis  by  Hall.  In 
Worthen’s  section  the  thickness  of  beds  i and  3 are  mentioned,  giving 
to  the  entire  Warsaw  formation  of  Hall  a thickness  of  something  over 
40  feet.  Hall  mentions  the  thickness  of  the  median  member  of  his 
formation  only,  and  he  considers  this  bed  to  be  the  typical  expression 
of  his  formation,  faunally  and  physically,  and  in  his  table  of  forma- 
tionsj  he  would  apparently  restrict  the  name  “Warsaw  limestone”  to 
this  median  bed  alone,  and  correlate  with  it  the  limestone  above  Alton 
and  the  beds  at  Spergen  Hill  and  Bloomington,  Indiana. 

In  a study  of  the  Warsaw  locality  by  the  writer  the  following  sec- 
tion, which  agrees  essentially  with  those  published  by  both  Hall  and 
Worthen,  although  worked  out  in  greater  detail,  was  carefully  meas- 
ured along  the  creek  east  of  the  town. 

Feet. 

11.  Dense,  bluish,  brecciated  limestone 10 

10.  More  or  less  cross-bedded  limestone,  yellow  on  weathered  surfaces 
and  granular  in  appearance,  containing  large  numbers  of  broken 
bryozoans;  sometimes  replaced  by  a calcareous  grit  or  sandstone..  8 
9.  Thin-bedded  bluish  limestone,  interbedded  with  calcareous  shales. 
Fossil  bryozoans  abundant,  especially  Lioclema  punctata  and  Arch- 


imedes wortheni 18 

8.  Fine  blue  shale  3 

7.  Hard,  light-colored  limestone,  with  few  poorly  preserved  fossils....  4 

6.  Fine  blue  shale  8 

5.  Magnesian  limestone  with  shaly  bands.  Fossils  poorly  preserved, 

usually  rare,  mostly  bryozoans 8 

4.  Bluish  shales  with  numerous  geodes  which  are  usually  smaller  than 

those  in  the  magnesian  limestone  beds  below 21 

3.  Magnesian  limestone  with  chert  bands 3 

2.  Magnesian  limestone  with  numerous  geodes.  Some  beds  more  or 
less  shaly.  Geodes  most  numerous  in  the  middle  part  of  the  bed. 
Fossils  poorly  preserved  and  rather  rare,  mostly  imperfect  bryo- 
zoans   15 

1.  Blue  or  grey  crystalline  limestone  with  many  fossils.  Thickness 

not  known,  the  bed  extending  below  river  level (exposed)  15 


In  this  section  beds  5 to  10  inclusive  comprise  the  original  Warsaw 
formation  of  Hall,  Bed  No.  9 being  the  typical  Warsaw  limestone  of 
that  author,  containing  the  large  numbers  Archimedes  and  other  bryo- 
zoans. Bed  No.  10  is  the  calcareous  grit  stone,  No.  3,  of  both  the 


* Geol.  Snrv.  111.  vol.  1,  pp.  8:?-84  ; also  Econ.  Geol.  111.  vol.  1,  p.  65. 
t Geol.  Surv.  111.  vol.  1,  p.  .*1:18  : also  Econ.  Geol.  111.,  vol.  1.  pp.  270-71. 
j Geol.  Surv.  Iowa,  vol  1,  pt.  1,  p.  109. 


^YELLER.] 


THE  SALEM  LIMESTONE. 


85 


Hall  section  and'the  Worthen  section.  This  bed  is  exceedingly  vari- 
able in  character,  being  at  times  a nearly  pure,  cross-bedded  limestone, 
as  at  the  quarry  back  of  the  school  building  at  Warsaw,  again  it  is  a 
sandstone  or  a calcareous  grit  stone.  Hall  mentions  the  occurrence  of 
small  quartz  pebbles  in  some  places.  When  the  formation  is  calcare- 
ous the  weathered  surfaces  exhibit  great  numbers  of  broken  bryozoans, 
more  or  less  imperfectly  preserved,  and  a few  brachiopods.  The  fauna 
from  the  quarry  near  the  school  house,  already  mentioned,  is  as 
follows : 

RMpidomella  duhia  (Hall). 

Spirifer  suhaequalis  (Hall). 

Fenestella  serratula  (Ulr). 

Fenestella  multispinosa  (Ulr). 

Rhoml)opora  (sp). 

Gystodictya  lineata  (Ulr). 

WortTienopora  spinosa  (Ulr). 

The  fauna  is  notable  for  the  entire  absence  of  Archimedes,  Glyp- 
topora  and  Lioclema,  genera  which  are  most  conspicuous  in  the 
fauna  of  the  subjacent  thin-bedded  limestones  and  shales.  On  the 
other  hand,  all  the  species  recognized  here  occur  commonly  and  are 
usually  among  the  more  abundant  in  the  limestones  further  south, 
near  Alton  and  elsewhere,  which  Hall  considered  as  representative 
of  his  Warsaw  limestone.  Some  or  all  of  the  species  also  occur  more 
or  less  sparingly  in  the  subjacent  bed  associated  with  the  abundantly 
represented  genera  mentioned  above.  It  is  evident,  therefore,  that 
although  this  uppermost  member  of  the  Warsaw,  as  defined  by  Hall, 
is  somewhat  closely  related,  faunally,  to  the  subjacent  and  more  typi- 
cal member  of  the  Warsaw  group,  it  is  this  upper  member  rather 
than  the  typical  Archimedes  and  Lioclema  bearing  bed  which  is  to  be 
correlated  with  the  so-called  Warsaw  limestone  above  Alton  and  else- 
where. Like  the  fauna  of  this  bed  at  Warsaw,  so  the  fauna  of  the 
limestone  farther  south  is  notable  for  the  extreme  rarity  and  usually 
by  the  entire  absence  of  members  of  the  genera  Archimedes,  Glyp- 
fopora  and  Lioclema,  and  with  the  possible  exception  of  Lioclema,  the 
species  of  these  genera  which  do  rarely  occur  are  usually  if  not  always 
distinct  from  those  of  the  Archimedes  bearing  bed  at  Warsaw. 

The  locality  in  the  region  to  the  south  of  Warsaw  where  the  beds 
under  discussion  are  best  exhibited  for  study  is  not  above  Alton, 
although  that  is  one  of  the  best  fossil  localities,  but  is  in  Missouri,  in 
the  neighborhood  of  Meramec  Highlands  west  of  St.  Louis,  The 
following  section  at  this  locality  is  compiled  from  several  carefully 
measured  se.ctions  in  the  bluffs  of  the  Meramec  river  and  up  the  tribu- 
tary valley  to  the  large  quarry  by  the  Frisco  Railroad  track  east  of 
the  Meramec  Highlands  station: 

Feet. 

17.  Grey,  granular  or  compact  limestone,  the  successive  beds  more  or 
less  variable  in  character,  with  numerous  horizontal  chert  hands. 
Fossils  rare.  The  top  of  this  limestone  extends  to  the  crusher 


plant  at  the  quarry,  by  the  railroad  track 40 

16.  Massive,  granular,  gray  limestone  with  few  fossils 10 

15.  Shaly  magnesian  beds 2 


86  * YEAR  BOOK  FOR  I907.  [Bull.  No.  8 

14.  Limestone  filled  with  fossils  of  the  Spergen  Hill  fauna 5 

13.  Limestone,  somewhat  shaly  and  magnesian  in  places 7 

12.  Fossiliferous  limestone  with  typical  Spergen  Hill  fauna 2 

11.  Limestone,  similar  to  that  above 4 

10.  Yellowish  limestone  filled  with  examples  of  a Rhynchonelloid  shell. . 2-6 

9.  Limestone  beds,  often  yellowish  in  color,  some  beds  shaley  and  ap- 
parently somewhat  magnesian,  other  beds  filled  with  bryozoans 

and  other  fossils 30 

8.  No  outcrops,  talus  probably  underlain  by  shale  in  the  lower  part 

and  limestone  above 26 

7.  Shale  exposed 2 

6.  No  outcrops,  probably  shale 13 

5.  Blue  shale,  fossiliferous,  Lioclema  punctata,  one  of  the  most  con- 
spicuous species 4 

4.  Blue  crystalline  limestone  with  many  Spirifers  at  top 4 

3.  No  outcrops,  probably  shales  in  large  part 18 

2.  Shaly  beds  with  intercalated  cherty  limestones 9 

1.  Blue  or  gray,  more  or  less  crystalline  limestone,  with  much  chert. . . 29 


In  this  section  three  rather  well  defined  divisions  may  be  recognized. 
The  first  division  includes  Beds  No.  i and  No.  2 and  is  well  exposed 
along  the  base  of  the  bluff  to  the  south  of  Meramec  highlands.  It 
consists  of  extremely  cherty  limestones  which  are  free  from  shale 
partings  below  but  with  more  and  more  conspicuous  shale  partings, 
and  beds  above.  These  beds  are  exposed  to  the  extent  of  38  feet  in 
the  measured  section  recorded  above,  but  all  these  beds  rise  to  the 
north  and  near  the  abrupt  bend  in  the  river  some  60  feet  are  exposed. 

The  second,  next  higher  division  consists  largely  of  shales  or  shaly 
limestone  as  is  evidenced  by  the  nearly  complete  talus  covering.  Only 
occasionally,  where  small  ravines  have  been  cut  into  the  bluff,  are  the 
b6ds  exposed.  No  examples  of  Archimedes  wortheni  have  been  ob- 
served in  this  bed,  but  Lioclema  punctata  does  occur  in  abundance 
where  fossils'  have  been  collected.  This  talus  covered  slope  between 
the  limestone  outcrops  below  and  above,  is  a conspicuous  feature 
in  the  bluffs  along  the  river  to  the  south  of  Meramec  high 
lands.  The  thickness  of  this  bed  is  not  accurately  known  since  the 
talus  is  banked  up  against  the  basal  part  of  the  superjacent  lime- 
stone, obscuring  the  lower  beds  of  that  division,  but  measured  from 
the  top  of  the  lower  division  to  the  first  exposures  of  the  limestone 
of  the  upper  division,  there  are  67  feet,  which  is  doubtless  too  great, 
the  excess  possibly  being  as  much  as  20  feet. 

The  third  division  is  best  exposed  in  the  quarry  already  mentioned 
and  comprises  beds  9 to  16,  inclusive.  The  basal  part  of  it  is  also 
well  seen  in  the  upper  portion  of  the  river  bluffs.  The  beds  of  this  di- 
vision are  more  or  less  variable  in  character,  some  of  them  being 
highly  fossiliferous,  the  fauna  being  the  typical  Spergen  Hill  fauna. 
Some  of  the  beds  near  the  base  are  not  unlike,  in  their  lithologic  charac- 
ters, the  calcareous  facies  of  the  uppermost  division  of  the  Warsaw 
group  in  Hancock  county,  Illinois.  These  beds  are  also  well  exposed 
in  the  cuts  along  the  Frisco  railroad  between  Meramec  Highlands  and 
Keyes  Summit,  and  again  at  the  tunnels  of  the  Missouri  Pacific  rail- 
road at  Barrett’s  Station.  Bed  No.  17,  in  the  general  section  here  de- 
scribed, differs  from  the  subjacent  limestone  beds  in  its  different  litho- 
logic characters,  in  the  almost  entire  absence  of  fossils  and  in  the 
presence  of  chert;  it  is  in  fact  the  basal  portion  of  the  true  St.  Louis 
limestone  and  need  not  be  considered  in  the  present  discussion. 


Weller.] 


THE  SALEM  LIMESTONE. 


87 


In  the  section  above  Alton  in  the  Mississippi  river  bluffs,  the  con- 
ditions are  essentially  the  same  as  those  at  Meramec  Highlands,  al- 
though the  continuity  of  the  beds  from  the  cherty  limestones  below 
with  shale  partings,  through  the  more  shaly  beds  of  the  second  division 
to  the  limestone  at  the  summit  is  not  so  well  shown  because  of  the 
erosion  of  the  Piasa  creek.  In  the  first  exposures  in  the  bluff  east 
of  the  mouth  of  Piasa  creek  near  Lock  Haven,  the  uppermost  beds  of 
the  shaly  division  are  exposed,  followed  by  the  limestones  bearing  the 
Spergen  Hill  fauna.  These  beds  with  an  easterly  dip  are  then  more  or 
less  continuously  exposed  in  the  base  of  the  river  bluff  to  Hopp 
Hollow  above  Alton  where  they  pass  below  the  superjacent  limestones, 
their  total  thickness  being  from  90  to  100  feet. 

In  correlating  the  Meramec  Highlands  section  and  that  in  the 
Mississippi  river  bluff  above  Alton, with  the  section  at  Warsaw,  the 
evidence  indicates  that  the  uppermost  bed  in  the  Warsaw  section,  the 
calcareous  grit  stone  of  Worthen  and  of  Hall,  with  a thickness  not 
exceeding  10  feet,  increases  in  thickness  to  the  south  until  it  attains  a 
depth  of  approximately  100  feet  in  the  neighborhood  of  Alton  and  St. 
Louis.  In  this  respect  this  bed  resembles  the  typical  St.  Louis  lime- 
stone which  becomes  much  attenuated  in  thickness  to  the  north. 
The  more  typical  expression  of  the  Warsaw  formation  of  Hall,  com- 
prising the  blue  shales  with  intercalated  thin  limestone  beds,  with 
the  Archimedes  and  Lioclema  fauna,  extends  to  the  south  with  no 
great  variation  in  thickness  where  it  is  exhibited  in  the  more  or  less 
talus  covered  shaly  bed  in  the  Meramec  Highlands  section.  The 
geode  beds  of  the  Warsaw  section,  usually  considered  as  the  upper 
limit  of  the  Keokuk  limestone,  are  not  present  in  the  more  southern 
region,  the  higher  Keokuk  beds  being  represented  by  the  cherty  lim- 
stones  with  shale  intercalations  in  the  Meramec  Highlands  section. 

The  original  Warsaw  formation  of  Hall  is  therefore  two-fold  in 
its  nature ; the  upper  division  being  of  but  subordinate  importance  in 
the  typical  section,  but  increasing  in  thickness  to  the  south  until  it  en- 
tirely overshadows  the  lower  and  more  typical  beds.  In  making  such 
a division  of  the  original  formation  the  name  Warsaw  may  be  re- 
stricted to  the  lower,  more  typical  part  which  includes  much  the  larger 
portion  of  the  beds  in  the  type  section.  The  upper  division,  as  it  is 
followed  to  the  south  from  Warsaw,  becomes  an  important  limestone 
formation  which  is  everywhere  characterized  by  the  Spergen  Hill  fauna 
of  Indiana,  and  may  be  definitely  correlated  with  the  Salem  limestone 
of  that  state. 

The  dual  nature  of  the  beds  referred  to  the  Warsaw  formation  by 
various  authors  was  recognized  by  Williams*,  although  he  was  unable 
to  straighten  out  the  confusion  from  a study  of  the  literature  alone. 
Keyesf  also  recognized  the  same  fact  and  united  all  the  beds  of  Hall’s 
original  section 'with  the  Keokuk,  while  the  so-called  Warsaw  lime- 
stones above  Alton  and  elsewhere  were  considered  as  forming  the 
basal  portion  of  the,  St.  Louis  limestone.  He  failed  to  recognize  the 


• Bull.  U.  S.  G.  S.  No.  80,  p.  169  (1891). 
t Iowa  G.  S.,  vol.  1,  pp.  70-71  (1893). 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


fact,  however,  that  these  limestone  to  the  south  were  really  the  more 
expanded  extension  of  the  subordinate  upper  member  of  the  Warsaw 
formation  in  its  typical  section. 

Relationship  of  Salem  Limestone  to  St.  Louis  Limestone. 

The  name  St.  Louis  limestone  was  first  applied  by  Englemann*  to  the 
limestones  which  underlie  ‘hhe  western  edge  of  the  great  Illinois  coal 
filed.”  The  definition  of  the  formation  was  inadequate  according  to 
recent  standards,  and  the  stratigraphic  relations  of  the  beds  were  mis- 
understood since  the  formation  was  supposed  to'  overlie  those  beds 
which  we  now  call  Cypress  sandstone  and  Chester  instead  of  being 
subjacent  to  them  as  is  now  known  to  be  the  case. 

In  the  1855  Report  of  the  Geological  Survey  of  Missouri,  both  Swal- 
low and  Shumard  discuss  the  St.  Louis  limestone,  and  both  are  in 
accord  in  their  interpretation  of  the  formation.  The  best  exposition 
of  the  conception  of  this  limestone  formation  held  by  these  men  is 
given  in  Shumard’s  report  on  St.  Louis  County,  f in  the  description 
of  the  geologic  section  along  the  line  of  the  Pacific  Railroad,  now  the 
Missouri  Pacific  Railroad.  In  this  description  the  beds  exposed  at 
both  tunnels  at  Barrett’s  Station,  which  beds  are  referred  tO'  the  .Salem 
limestone  in  this  paper,  are  distinctly  described  as  belonging  to  the 
“Archimedes  limestone,”  a formation  subjacent  to  the  St.  Louis  lime- 
stone, and  this  relation  is  clearly  shown  in  the  graphic  section  accom- 
panying the  report.  In  the  description  of  the  Archimedes  limestone  by 
Swallow!  the  strata  on  the  Des  Moines  river  and  near  Keokuk,  Iowa, 
are  mentioned  in  such  a manner  as  to  show  clearly  that  his  Archimedes 
limestone  is  considered  as  essentially  the  equivalent  of  the  beds  called 
Warsaw  by  Hall  at  a later  date.  It  is  clear  then  that  these  authors 
who  were  the  first  to  define  the  St.  Louis  limestone  in  a manner  at  all 
adequate  excluded  from  that  formation  these  beds  which  we  call 
Salem  limestone. 

Hall’s  interpretation  of  these  beds  has  already  been  discussed.  He 
followed  essentially  the  interpretation  of  Swallow  and  Shumard,  and 
considered  this  formation  as  distinct  from  the  St.  Louis  limestone,  call- 
ing it  the  Warsaw  limestone. 

Worthen  departed  from  the  interpretation  of  these  earlier  geologists 
and  considered  the  beds  under  discussion  as  a part  of  his  St.  Louis 
group, § and  included  also  under  this  head  the  typical  Warsaw  lime- 
stone of  Hancock  county.  It  is  clear,  however,  that  Worthen  did  not 
intend  to  completely  dispense  with  the  name  Warsaw  as  a formation 
name  as  he  not  infrequently  mentioned  the  Warsaw  division  of  the 
St.  Louis  in  his  county  reports,  but  he  at  no  time  distinguished  between 
the  typical  Warsaw  as  that  formation  would  be  restricted  by  the 
writer  and  the  higher  division  here  called  the  Salem  limestone.  Wor- 
then’s  usage  of  St.  Louis  as  a group  name  in  which  was  included  a 


* Am.  Jour.  Sci.  2nd  Ser.  ; vol.  3,  p.  119  (1847). 
list  and  2nd  Ann.  Rep.  Geol.  Surv.,  Mo.,  pt.  2,  p.  169,  (1855.) 
tLoc.  cit..  pt.  1.  p.  95. 

§Geol.  Surv.  111.,  vol.  1,  p.  83  (1866);  also  Econ.  Geol.  111.,  vol.  1,  p.  65,  (1882.) 


Weller.] 


THE  SALEM  LIMESTONE. 


89 


subordinate  division,  the  St.  Louis  limestone  proper,  has  led  to  some 
confusion  among  more  recent  authors,  and  the  more  general  conception 
of  late  years  has  been  that  the  St.  Louis  limestone  in  its  original  defi- 
nition included  all  these  limestones  under  consideration. 

Extended  field  observations  by  the  writer  have  shown  that  the  Salem 
limestone  is  as  clearly  defined  a stratigraphic  unit  in  the  Mississippian 
series  of  the  Mississippi  valley  as  any  of  the  formations  recognized. 
The  formation  may  be  easily  distinguished  from  the  superjacent  St. 
Louis  limestone  on  lithologic  characters  alone,  and  when  the  faunal 
characters  are  considered  the  difference  is  even  more  striking.  The 
formation  includes  beds  of  m.ore  or  less  variable  lithologic  characters, 
the  variable  character  being  perhaps  more  pronounced  in  the  northern 
than  in  the  southern  outcrops.  Usually  the  formation  is  nearly  or  quite 
free  from  chert.  Throughout  its  extent  it  contains  important  beds  of 
light-colored,  nearly  white  limestones,  which  are  not  infrequently  more 
or  less  oolithic  in  texture.  In  some  cases  the  apparent  oolithic  grains 
are  the  shells  of  a small  foramifera  Endothyra  bailey,  but  again  there 
are  true  oolites.  These  lighter  colored  beds  have  a peculiar  method  of 
weathering  which  is  not  often  observed  in  any  other  of  the  Mississip- 
pian formations.  The  more  or  less  vertical  faces  of  the  outcrops  scale 
off  in  a transverse  direction  to  the  bedding  in  rather  thin,  irregular 
flakes  from  three  to  six  inches  across  and  an  inch  or  less  in  thickness, 
this  fracturing  of  the  rock  evidently  being  due  to  frost  action.  Fine 
grained,  bluish  grey  or  buff  colored  magnesian  beds  of  varying  thick- 
ness are  not  infrequently  interbedded  with  the  more  nearly  pure  lime- 
stones, and  at  two  localities,  one  in  Madison  county  and  the  other  in 
St.  Clair  county,  beds  of  this  character  have  been  extensively  mined  for 
the  manufacture  of  hydraulic  cement,  although  the  deposits  have  not 
been  worked  during  recent  years. 

The  purer  limestones  in  this  formation  are  usually  more  or  less 
abundantly  fossiliferous,  and  the  fossils  often  occur  in  an  excellent 
state  of  preservation.  Among  the  most  conspicuous  forms  are  the 
bryozoans,  belonging  to  the  genera  Fenestela,  Polypora  and  Crysto- 
dictya,  which  often  present  a nearly  pure  white  color  in  the  slightly 
darker  matrix. 

The  Salem  limestone  does  not  contain,  at  least  as  a conspicuous  ele- 
ment, beds  of  dense,  compact,  bluish  gray  limestones  with  conchoidal 
fracture  and  with  a texture  almost  of  lithographic  stone,  such  as  are 
commonly  present  in  the  St.  Louis  limestone  ; neither  are  there  present 
the  brecciated  beds  which  are  sO'  characteristic  of  the  St.  Louis.  The 
two  formations  may  also  be  differentiated  by  reason  of  the  abundance 
of  fossils  in  the  Salem  and  the  comparative  rarity  of  them  in  the  St. 
Louis,  at  least  in  such  a condition  of  preservation  as  to  be  readily  de- 
termined. In  fact,  most  of  the  so-called  St.  Louis  fossils  in  the  Missis- 
sippi valley  are  in  reality  from  the  Salem  limestone. 

Although  there  is  no  structural  break  between  the  Salem  and  the 
St.  Louis,  and  the  sedimentation  was  evidently  continuous  from  the 
lower  to  the  upper  formation,  except  in  the  extreme  northern  exten- 
sion of  the  beds  where  there  is  a possible  slight  uniformity,  the  dividing 
line  between  the  two  formations  in  any  given  section  may  usually  be 


90 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


easily  recognized  within  a thickness  of  from  five  to  ten  feet.  This 
separation  may  ordinarily  be  made  on  the  lithographic  characters  alone, 
but  with  the  aid  of  the  fossils  no  mistake  can  be  made. 

The  Meramec  Group  of  Ulrich. 

Ulrich  has  defined  as  the  Meramec  group*  those  beds  included  in  the 
St.  Louis  group  of  Worthen,  the  name  Meramec  being  substituted  for 
St.  Louis  in  order  to  avoid  the  usage  of  that  name  in  two  senses.  In 
this  group  he  includes  the  Warsaw,  Spergen  and  St.  Louis.  The 
Warsaw  formation,  however,  should  from  both  physical  and  faunal 
reasons  be  more  properly  joined  with  the  subjacent  Keokuk  formation, 
which  would  bring  it  into  the  Osage  group,  and  there  is  no  more  reason 
for  associating  the  Salem  and  the  St.  Louis  in  one  larger  division  than 
in  bringing  the  St.  Louis  and  the  superjacent  St.  Genevieve  fonna- 
tions  together.  It  would  seem,  therefore,  that  in  so  far  as  the  Illinois 
stratigraphy  is  involved  the  recognition  of  a Meramec  group  is  of 
doubtful  utility. 

Geographic  Distribution  of  Salem  Limestone  in  Illinois. 

Hancock  county — As  has  already  been  indicated,  the  northermost 
point  where  the  Salem  limestone  has  been  recognized  is  at  Warsaw,  in 
Hancock  county,  where  the  formation  is  represented  by  a bed  of  grit, 
or  arenaceous  limestone  of  variable  lithologic  character,  which  reaches 
a thickness  of  only  eight  to  ten  feet.  There  is  no  clearly  defined  un- 
conformity at  this  locality  upon  the  subjacent  Warsaw  limestone  and 
shale,  but  the  presence  of  the  arenaceous  beds  which  sometimes,  accord- 
ing to  Hall,  contain  quartz  pebbles,  is  at  least  suggestive  of  an  uncon- 
formity. The  unconformity,  however,  if  such  be  present,  is  only  a 
slight  one,  since  a numberof  species  of  fossils  are  common  to  the  War- 
saw formation  and  the  superjacent  Salem  limestone.  The  species  of 
fossils  which  have  been  identified  in  the  Salem  limestone  of  Hancock 
county  have  already  been  mentioned. 

McDonough,  Schuyler,  Adams,  Brozun,  Pike,  Greene  and  Jersey 
counties — In  these  counties  no  examination  of  the  Salem  limestone  has 
been  made  by  the  writer  except  in  Adams  and  Calhoun.  In  all  of 
them,  however,  the  St.  Louis  limestone  is  described  by  Worthen, f and 
from  reading  his  descriptions  one  can  usually  recognize  certain  of  the 
lower  beds  which  should  doubtless  be  referred  to  the  Salem  lime- 
stone. In  Adams  county,  where  the  formation  has  been  seen,  but  not 
carefully  studied  the  beds  are  similar  in  character  to  the  equivalent 
beds  further  south.  In  Calhoun  county  the  Salem  limestone  occurs 


*U.  S.  G.  S..  Prof.  pap.  No.  36,  pp.  28-34. 

tMcDonouffh  Co..  Geol.  Surv.  111.,  vol.  5,  p.  260;  also  Econ.  Geol.  of  111.  vol.  3,  p.  273.  Schuy- 
ler Co.,  Geol.  Surv.  111.  vol.  4,  p.  84;  also  Econ.  Geol.,  vol.  2,  p.  330.  Adams  Co.,  Geol.  Surv.  111. 
vol.  4,  pp.  51-53;  also  Econ.  Geol.  111.,  vol.  2,  pp.  293-396.  Brown  Co.  Geol.  Surv.  111.,  vol.  4',  pp. 
68-69;  also  Econ.  Geol.  111.,  vol.  2,  pp.  313-314.  Pike  Co.,  Geol.  Surv.  111.,  vol,  4,  p.  32;  also  Econ. 
Geol.  111.,  vol.  2.  p.  272.  Calhoun  Co.,  Geol.,  Surv.  111.,  vol.  4,  p.  15;  also  Econ.  Geol.  111.,  vol.  2, 
p.  25^  Greene  Co.,  Geol.  Surv.  111.,  vol.  3,  pp  127-128;  also  Econ.  Geol.  111.,  vol.  2,  pp,  51-52. 
Jersey  Co.,  Geol.  Surv.  111.,  vol.  3,  pp.  111-112;  also  Econ.  Geol,  111.,  vol.  2,  pp.  32-33. 


Weller.  1 


THE  SALEM  LIMESTONE. 


91 


in  only  a single  limited  area  adjacent  to  the  Cap  au  Gres  fault.  The 
exposures  are  much  weathered  and  appear  to  be  porus,  brown,  mag- 
nesian limestone  in  which  the  fossils  are  imperfectly  preserved.* 

In  passing  southward  from  Hancock  county  the  formation  becomes 
thicker,  but  does  not  attain  its  normal  thickness  of  nearly  100  feet  until 
Madison  county  is  reached. 

Madison  county — In  Madison  county  the  Salem  limestone  is  exposed 
in  the  Mississippi  river  bluffs  from  near  the  mouth  of  Piasa  creek  to 
Hopp  Hollow,  two  miles  above  Alton.  In  the  bluffs  %.  mile  below 
the  mouth  of  Piasa  creek  the  lower  beds  of  the  formation  are  exposed 
resting  upon  the  subjacent 'Warsaw  shales,  In  passing  down  the  river 
higher  and  higher  beds  are  exposed  by  reason  of  the  gentle  dip  of 
the  rocks  to  the'  east,  until,  at  Hopp  Hollow,  the  formation  passes  be- 
neath the  surface.  A series  of  measured  sections  have  been  studied 
in  these  bluffs,  which  give  the  total  thickness  of  the  formation  as  94 
feet. 

The  first  of  these  sections  is  54  of  a mile  east  of  the  Piasa  creek, 
above  the  tracks  of  the  C.  P.  & St.  L.  Railroad,  in  which  the  following 
beds  were  recognized. 

Feet 


13  Thin  bedded  limestone,  very  fine  in  texture,  of  grey  or  yellowish 
color;  beds  % to  1 inch  in  thickness,  almost  shale-like  in  ap 

pearance,  93-100  feet 7 

12  Talus  covered  slope.  79-93  feet 14 

11  Limestone  of  variable  character,  apparently  more  or  less  mag- 
nesian, some  beds  more  magnesian  than  others.  Mostly  rather 
thin  bedded,  but  some  beds  1 foot  in  thickness.  Partially  covered 

with  talus.  69-79  feet 10 

10  Gray  or  buff  limestone,  granular  in  texture,  heavy  bedded,  with 

scaly  weathered  surface.  Fossils  abundant.  (W93).  58-69  feet  11 
9 Fine  grained,  gray  or  blue  magnesian  bed,  similar  in  texture  to 

the  cement  bed  formerly  mined  near  Clifton.  56-58  feet 2 

8 Limestone  with  coarse,  irregular  texture,  with  numerous  crinoid 

stems  and  bryozoans  showing  on  the  weathered  surface.  55-56  feet  1 

7 Yellowish,  impure  magnesium  limestone.  54-55 1 

6 Fine  grained  granular  limestone,  gray  or  yellowish  in  color. 

Good  fossils  not  common  although  the  entire  bed  is  composed 

of  worn  organic  fragments.  42-54  feet 12 

5 Impure,  brownish  limestone,  more  or  less  thin  bedded.  39-42  feet. . 3 

4 Yellowish,  granular,  crystalline  limestone,  with  abundant  fossils, 

some  of  which  are  well  preserved.  (W92).  34%-39  feet 45^ 

3 Limestone  similar  to  that  above  but  with  the  fossils  less  per- 
fectly preserved.  This  bed  is  in  two  ledges  with  a shaly  band 

between.  28-345^  feet  65^ 

2 Talus  slope  with  no  exposure.  3-28  feet  25 

1 Blue  shale  exposed  a few  rods  above  the  point  where  the  re 

mainder  of  the  section  was  measured.  0-3  feet  3 


In  this  section  bed  No.  i is  doubtless  a part  of  the  shaly  Warsaw 
formation,  although  no  fossils  were  secured.  The  talus  slope  between 
3 and  28  feet  is  probably  in  large  part  underlain  by  the  Warsaw 
shales,  although  the  basal  part  of  the  superjacent  Salem  limestone 
may  also  be  covered.  Be'ds  Nos.  3 to  13  are  all  to  be  included  in  the 
Salem  limestone. 


tBull.  111.  State  Geol.  Surv.,  No.  4,  p.  228. 


92 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


The  next  section  in  the  series  is  in  the  bluff  above  Riehl’s  Station, 
on  the  C.,  P.  & St.  L.  railroad,  where  the  following  beds  were  recog- 
nized : 


Feet. 


9 Granular,  gray  limestone,  with  scaly  weathering,  thinner  bedded 
above,  the  weathered  surface  covered  with  fragmentary  crinoid 

stems  and  other  fossils.  54-65  feet  11 

8 Oolitic  limestone  filled  with  fossils  (W95).  52-54  feet 2 

7 Dense,  more  or  less  irregularly  bedded  limestone,  apparently 

somewhat  magnesian.  47-52  feet  5 

6 Granular,  gray  or  yellowish  limestone  exhibiting  scaly  weathering. 

37-47  feet  10 

5 Heavy  bedded  limestone  with  many  fossils.  26%-37  feet 10% 

4 Limestone  which  is  apparently  in  part  magnesian.  Fossil  bryo- 

zoans.  24%-26%  feet  2 

3 Heavy  ledge  of  limestone  which  is  probably  the  same  as  bed  No.  3 

in  the  last  section.  20-24%  feet  4% 

2 Limestone,  variable  in  character  with  a one  foot  fossil  band  at 

elevation  12-13  feet  (W94).  10-20  feet  . 10 

2 Blue,  gritty  shales,  similar  to  that  at  the  base  of  last  section. 

0-10  feet  10 


The  shale  at  the  base  of  this  section,  bed  No.  i,  is  the  same  as  the 
shale  at  the  base  of  the  last  section  and  is  doubtless  a part  of  the 
Warsaw  formation.  The  remainder  of  the  section  is  entirely  within 
the  Salem  limestone. 

Below  Riehl’s  Station  these  beds  are  again  well  exposed,  although 
the  Warsaw  shales  at  the  base  soon  pass  below  the  surface  because 
of  the  easterly  dip  of  the  strata.  A little  distance  east  of  the  railroad 
trestle  below  the  station  a small  collection  of  fossils  was  made  from 
No.  4 of  the  above  section  where  this  bed  has  dropped  to  a level  of  about 
16  feet  above  the  railroad  track  (W96),  and  another  collection  from 
the  same  locality  from  the  same  limestone  just  above  the  last,  six 
inches  to  one  foot  in  thickness  (W97). 

The  next  section  in  this  series  starts  from  the  mouth  of  a small 
ravine  known  as  Hull’s  Hollow  about  one  and  one-half  miles  below 
Clifton  Terrace  station,  and  was  measured  to  the  top  of  the  bluff 
west  of  the  ravine.  The  beds  recognized  are  as  follows : 

Feet. 


15  Heavy,  brecciated  or  conglomeratic  limestone.  171-183  feet 12 

14  Limestone  of  variable  character,  thick  and  thin  beds,  some  layers 

apparently  magnesian  and  some  layers  shaly.  117-171  feet....  54 

13  Brecciated  limestone.  110-117  feet  7 

12  Hard,  gray  limestone  with  numerous  plates  and  spines  of 

ArcJiaeocidaris  on  the  weather  surfaces.  102-104  feet 2 

11  Hard,  gray  limestone.  97-102  feet  5 

10  Limestone  ledges  more  or  less  talus  covered,  some  beds  shaly. 

61-97  feet  36 

9 Hard,  fossiliferous  limestone  (W45).  59-61  feet 2 

8 Limestone,  mostly  in  heavy  beds,  with  some  thinner  shaly  beds. 

Fossils  not  abundant.  38-59  feet  21 

7 Buff  colored,  shaly,  magnesian  bed.  34-38  feet 4 

6 Hard,  fine  grained,  gray  limestone  exposed  in  lower  part  of  old 

quarry.  26-34  feet  8 

5 Talus  covered.  20-26  feet 6 


Weller.] 


THE  SALEM  LIMESTONE. 


93 


4 Gray,  fossiliferous  limestone  forming  the  lower  waterfall  near 

the  mouth  of  the  ravine  (W44),  10-20  feet 10 

3 Hard  limestone  ledge,  oolitic  in  part,  with  a large  Spergen  Hill 

fauna  (W43).  9-10  feet 1 

2 Earthy  magnesian  bed,  with  texture  similar  to  that  of  the  “cement 

bed”  formerly  mined  near  Clifton.  7-9  feet 2 

1 No  exposure  from  river  level.  0-7  feet 7 


In  this  section  beds  Nos.  i-g  may  be  included  in  the  Salem  lime- 
stone, the  higher  beds  being  a part  of  the  St.  Louis  limestone.  It  was 
probably  from  beds  Nos.  3 and  4 of  this  section,  or  from  Hopp  Hollow, 
the  section  next  to  be  described,  that  Hall’s  material  mentioned  as 
coming  from  above  Alton  in  his  paper  on  the  Spergen  Hill  fauna  of 
Indiana,  was  obtained.  The  oolitic  portion  of  bed  No.  3 is  especially 
rich  in  fossils  and  contains  a large  portion  of  the  same  species,  in  a 
very  perfect  condition  of  preservation,  as  the  Spergen  Hill  and  Bloom- 
ington beds  of  Indiana.  This  bed  is  also  probably  the  equivalent  of 
bed  No.  8 in  the  Riehl’s  Station  section,  where  it  occurs  at  an  elevation 
of  from  52  to  54  feet  above  the  railroad  track. 

In  the  quarry  of  the  Blue  Grass  Crusher  Co.,  just  west  of  Hopp 
Hollow,  the  upper  beds  of  the  Salem  limestone  are  exposed  with  the 
superjacent  St.  Louis  limestone.  The  measured  section  at  this  point 
is  as  follows : 

Feet. 


13  Brecciated  limestone.  130-142  feet  12 

12  Gray  to  buff  limestone,  becoming  somewhat  thinner  bedded  above. 

108-130  feet  22 

11  Brown  limestone.  105^-108  feet  2% 

10  Dense  gray  limestone  with  numerous  sections  of  brachiopods 

shown  upon  the  weathered  surface.  103%-105i/^ 2 

9 Gray  limestone,  thin  bedded  in  one  inch  layers,  with  occasionally 
brownish  layers.  * Ripple  marked  surface  at  elevation  83. 

81-103  Va  feet  22  Va 

8 Limestone,  heavy  bedded  below,  becoming  thinner  bedded  above 

to  top  of  quarry.  64-81  feet  17 

7 Yellow,  earthy  layer,  probably  magnesian.  60-64  feet 4 

6 Impure  limestone  in  thick  and  thin  beds,  some  shaly  layers,  six 
inches  of  blue  clay  shale  at  the  base.  Towards  the  top  the  beds 

become  thicker,  being  hard,  dense  limestone.  47-60  feet 13 

5 Impure  limestone  with  much  chert,  somewhat  earthy  in  texture. 

Yellowish  in  color,  probably  magnisian.  34-47  -feet 13 

4 Magnesian  (?)  limestone,  shaly  below.  31-34  feet 3 

3 Dense  limestone  with  some  chert.  26-31  feet 5 

2 Limestone  similar  to  that  below,  but  more  dense,  a little  darker  in 

color,  with  some  hard  masses  and  some  chert.  18-26  feet 8 

1 Light  gray,  granular  limestone,  with  an  abundance  of  fossils  in 

pockets  and  bands.  No  chert  (W42).  0-18  feet 18 


In  this  section  bed  No.  i represents  the  summit  of  the  Salem  lime- 
stone, all  the  higher  beds  being  of  the  St.  Louis  limestone.  The  fauna 
of  this  bed  is  somewhat  extensive  and  is  the  typical  Spergen  Hill 
fauna  of  Indiana.  Below  this  quarry  the  Salem  quickly  passes  out 
of  sight  by  reason  of  the  eastward  dip  of  the  strata. 

St.  Clair  county. — On  the  Illinois  side  of  the  Mississippi  river  the 
outcrop  of  the  Mississippian  beds  is  interrupted  between  the  northern 
part  of  Madison  county  and  the  southern  part  of  St.  Clair,  by  the 
broad  American  bottom,  the  alluvial  deposits  extending  eastward  to 


94 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


beyond  the  line  separating  the  Mississippian  and  the  Pennslyvanian 
series.  At  the  point  where  the  bluffs  of  Mississipian  limestone  re- 
appear in  southern  St.  Clair  county,  the  beds  exposed  are  typical 
St.  Louis  limestone,  with  a gentle  northerly  dip.  Following  the  bluffs 
to  the  south  the  beds  arise  until  the  Salem  limestone  appears  in  the 
base  of  the  bluffs  and  finally  constitutes  nearly  or  quite  all  of  the 
limestone  beds  exposed  in  the  bluff.  Before  the  Monroe  county  line 
is  reached,  however,  the  crest  of  an  anticline  is  passed  and  the  beds 
again  pass  beneath  the  surface.  In  the  point  of  the  hill  just  northwest 
of  Sugar  Loaf  school  house  the  St.  Louis  limestone  beds  of  the 
southwestern  limb  of  the  anticline  exhibit  a dip  of  31  degrees,  which 
is  much  more  abrupt  than  the  dip  of  the  opposite  limb. 

In  the  upper  part  of  the  ravine  extending  back  from  the  river  at 
Sugar  Loaf  school  house  where  the  old  cement  mine  is  located,  a 
good  section  is  exposed,  the  base  of  the  section  being  shown  in  the 
bank  of  the  creek  back  of  the  house  occupied  by  Mr.  James  Bergen, 
and  the  upper  beds  at  the  cement  mine. 

Feet. 

13  Ledges  of  thick  and  thin  bedded  limestones,  more  or  less  granular 


and  crystalline  in  texture,  usually  light  in  color  with  gray  or 
brown  tints,  some  thin  beds  apparently  magnesian  and  occasion- 
ally shaly  partings.  All  these  beds  are  more  or  less  covered 

with  talus.  47-80  feet  33 

12  Cement  bed.  Earthy,  bluish  or  gray  magnesian  limestone  with 
uniform  texture.  Exactly  similar  in  texture  to  the  cement  bed 
in  the  Salem  limestone  near  Clifton  Terrace  in  Madison  county. 

39-47  feet  8 

11  Thin  bedded  limestones.  36-39  feet  3 

10  Thin  bedded  blue  limestone  with  large  numbers  of  fossil  Spirifers 

(W250).  35-36  feet  : 1 

9 Thin  bedded  limestone  similar  to  the  beds  above.  33-35  feet. ...  2 

8 Limestone  similar  to  that  above  with  numerous  fossils  (W249). 

32-33  feet  1 

7 Thin  bedded  limestone  with  bands  of  shales.  30-32  feet 2 

6 Possiliferous  limestone  (W248).  29-30  feet  1 

5 Buff  or  blue  shales  with  occasional  thin  beds  or  lenses  of  lime- 
stone. 18-29  feet  11 

4 Buff  colored  fossiliferous  shales  (W247).  16-18  feet  2 

3 Buff  or  blue  shales  with  occasional  thin  beds  or  lenses  of  lime- 
stone. 6-16  feet  10 

2 Irregularly  thin  bedded,  fossiliferous  limestone  strata  with  inter- 

bedded  shale  (W246).  4-6  feet  2 

1 Blue  and  buff  fossiliferous  shales  (W245)  0-4  feet 4 


In  this  section  a little  over  40  feet  of  the  higher  beds  including  the 
cement  bed  are  referable  to  the  Salem  limestone.  The  lower  beds 
represent  the  shaly  Warsaw  formation  as  it  is  so  well  developed  in  St. 
Louis  county,  Missouri,  and  as  it  occurs  in  northern  Madison  county. 

Monroe  county — A quarry  in  the  Salem  limestone  was  formerly 
worked  in  the  southwest  quarter  of  section  14,  about  a mile  southeast 
of  Columbia.  At  this  point  a thickness  of  about  48  feet  of  limestone 
is  exposed  which  is  more  or  less  variable  in  color  and  texture.  Its 
characters  agree  well  with  those  of  the  Salem  limestone  exposed  in 
the  river  bluffs  of  southern  St.  Clair  county.  In  the  bed  of  the  quarry 
is  a shaly  bed  which  is  abundantly  fossiliferous,  the  fauna  being  a 


Weller.] 


THE  SALEM  LIMESTONE. 


95 


characteristic  assemblage  of  the  vSalem  limestone  (U  48).  At  another 
locality  one  and  one-half  miles  south  of  Columbia,  in  the  southeast 
quarter  of  section  27,  the  Salem  limestone  is  exposed.  The  rock  at 
this  locality  is  similar  in  its  physical  and  faunal  characters  to  the  beds 
of  similar  age  further  north.  Fossils  are  somewhat  abundant  (U  56). 

At  both  of  the  last  localities  the  Salem  limestone  has  been  brought 
to  the  surface  by  the  anticlinal  folding  of  the  beds,  exhibited  in  the 
river  bluff  in  southern  St.  Clair  county.  In  the  Mississippi  river 
bluffs  the  .Salem  limestone  is  not  exposed  in  Monroe  county  until  a 
point  south  of  Fountain  creek  is  reached  where  the  rocks  begin  to 
rise  to  the  anticlinal  axes  exhibited  in  the  outcrop  of  the  Kimmswick 
limestone  at  Valmeyer.  The  outcrops  in  this  portion  of  the  bluff  have 
not  been  studied  in  detail,  and  no  collections  have  been  made,  but  the 
observations  which  have  been  made  indicate  that  the  characteristics 
of  the  formation  are  not  different  here  from  other  localities.  Im- 
mediately south  of  the  Valmeyer  anticline,  the  Salem  limestone  is  not 
clearly  shown  in  the  Mississippi  river  bluffs.  All  the  beds  which  are 
exposed  where  one  would  expect  to  find  the  Salem  limestone  seem  to 
belong  in  the  St.  Louis  formation ; the  Salem  is  either  covered  with 
the  talus  at  the  foot  of  the  bluff  or  the  strata  have  been  faulted  in  such 
a manner  as  to  obscure  the  beds  in  question.  This  region  has  been 
examined  only  in  a hasty  manner  and  a few  days  detailed  work  will 
doubtless  make  the  relations  clear. 

Below  Chalfin  Bridge  P.  O.  the  Salem  limestone  again  appears  in 
the  base  of  the  bluffs,  the  summit  of  the  formation  rising  to  a height 
of  59  feet  above  the  bottom  lands  in  the  northwest  corner  of  section 
7,  a little  over  one-half  mile  southeast  of  the  post  office.  At  this 
point  the  following  section  was ‘Carefully  measured. 


Feet. 

9 Hard,  blue  or  gray  limestones,  more  or  less  variable  in  texture 
and  variously  bedded,  having  the  typical  characteristics  of  the 

St.  Louis  limestone.  213-231  feet 18 

8 Limestone  filled  with  large  and  small  colonies  of  the  coral  Lith- 

ostrotion.  198-213  feet 15 

7 Limestones  in  every  way  similar  to  those  above  the  corraline 

bed.  151-198  feet  47 

6 Limestone  filled  with  fossil  cephalopods  of  various  genera  (W237). 

150-151  feet 1 

5 Limestone  beds  similar  to  those  higher  up,  passing  into  an  exceed- 
ingly hard,  dense  blue  limestone,  just  beneath  the  cephalopod 

layer.  86-150  feet  64 

4 Hard,  siliceous  limestone  having  almost  the  appearance  of  a very 

hard  sandstone.  85-86  feet 1 

3 Beds  variable  in  character,  for  the  most  part  magnesian,  earthy 
limestones,  buff  or  brown  in  color,  with  bluish  beds  near  the 

top.  59-85  feet  16 

2 Light  colored,  grayish  or  yellowish  limestones,  having  the  features 
characteristic  of  the  Salem  limestone.  Fossils  common  (W236). 

30-59  feet  29 

1 No  exposures  to  the  level  of  the  bottom  land.  0-30  feet .!.]  30 


The  Salem  limestone  is  represented  by  bed  No.  2 of  this  section, 
this  being  the  upper  portion  of  the  formation.  The  higher  beds  are 
all  St.  Louis  limestone. 


96 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


One  mile  southeast  of  the  last  section,  opposite  the  residence  of  Mr. 
William  Maeys,  the  Salem-St.  Louis  contact  is  only  25  feet  in  eleva- 
tion above  the  river  bottom,  the  section  being  as  follows : 


5 Thin  bedded  magnesian  limestones.  84-94  feet 10 

4 Chert  band.  83-84  feet  1 

3 Magnesian  limestone,  quarry  ledge.  77-83  feet 6 

2 Thin  bedded  magnesian  limestones.  25-77  feet  52 

1 Limestone  having  the  characteristic  features  of  the  Salem  exposed 

above,  covered  with  talus  below.  0-25  feet  25 


From  this  point  the  summit  of  the  Salem  limestone  rises  gently  and 
regularly  for  a distance  of  a little  over  three  and  one-fourth  miles, 
to  the  ravine  which  intersects  the  bluff  about  one  mile  below  the 
northwestern  boundary  of  the  Renault  grant,  just  south  of  which 
the  Salem-St.  Louis  contact  occurs  at  an  elevation  of  66  feet  above 
the  river  bottom.  Just  below  this  point  the  continuity  of  the  forma- 
tion is  interrupted  by  a fault  and  one-half  mile  to  the  southeast  the 
contact  is  recognized  at  an  elevation  of  176  feet. 

Continuing  along  the  bluffs,  the  beds  rise  gently  at  first  and  then 
more  abruptly  to  an  anticlinal  axis  which  intersects  the  bluff  opposite 
the  village  of  Renault.  Over  the  anticline  the  Salem  limestone  beds 
have  been  practically  removed  so  that  the  contact  between  it  and  the  St. 
Louis  limestone  has  not  been  seen,  but  the  base  of  the  Salem,  resting 
upon  the  subjacent  Keokuk-Warsaw  formation,  may  be  seen  at  an  ele- 
vation of  145  feet  in  the  bluff  just  below  the  intersection  of  the  road 
to  Renault  with  the  river  road  in  the  northeast  quarter  of  Section  i. 
Assuming  the  thickness  of  the  Salem  as  100  feet,  which  is  as  close  as 
it  can  be  estimated  for  Monroe  county,  the  Salem-St.  Lauis  contact 
would  be  at  an  elevation  of  245  feet.  Continuing  to  the  southeast  the 
beds  descend  rapidly  upon  the  southern  limb  of  the  anticline,  the  Salem- 
St.  Louis  contact  having  an  elevation  of  95  feet  about  one  mile  from 
Randolph  county  line,  and  65  feet  at  a point  about  one-half  mile  below. 
Before  reaching  the  Randolph  county  line,  the  formation  has  passed 
below  the  level  of  the  river  bottom  and  is  not  again  exposed  until  the 
neighborhood  of  Grand  Tower,  in  Jackson  county,  is  reached. 

Throughout  Monroe  county  wherever  the  formation  occurs,  the  litho- 
logic expression  of  the  Salem  limestone  is  uniform  and  it  can  be  easily 
recognized.  It  is  furthermore  characterized  throughout  by  the  char- 
acteristic Spergen  Hill  fauna.  At  some  points  certain  beds  of  the  lime- 
stone might  be  satisfactorily  and  profitably  developed  as  building 
stone.  The  Iron  Mountain  Railroad,  running  the  entire  length  of  the 
county  between  the  bluffs  and  the  river  would  furnish  good  transporta- 
tion facilities.  The  locality  where  the  formation  seems  to  be  most 
favorably  situated  for  quarry  purposes  is  about  one  mile  above  the 
Randolph  county  line  in  the  point  of  the  bluff  west  of  the  road  which 
runs  in  a northerly  direction  to  the  village  of  Renault.  At  this  point 
the  rock  occurs  in  more  than  usually  heavy  beds ; it  is  apparently 
uniform  in  texture  and  color,  and  resists  the  action  of  weathering. 
Furthermore,  it  is  not  covered  at  this  point  by  heavy  ledges  of  the 
superjacent  St.  Louis  limestone  and  a large  quarry  might  be  opened 
with  but  a minimum  amount  of  stripping.  Careful  tests  would  be 


Wellek.] 


THE  SALEM  LIMESTONE. 


97 


necessary  to  determine  whether  the  rock  at  this  point  would  be  equal 
for  purposes  of  construction,  to  the  celebrated  “Bedford  stone”  of 
Indiana,  but  the  superficial  examination  of  the  locality  would  seem  to 
indicate  this  to  be  the  case. 

Jackson  county — In  the  vicinity  of  Grand  Tower,  in  Jackson  county, 
three  conspicuous  hills  rise  abruptly  above  the  broad  alluvial  plain 
which  extends  from  the  Mississippi  to  the  Big  Muddy  river.  The 
first  and  larg-est  of  thes^e  hills  is  known  as  “Big  Hill”  or  “Fountain 
Bluff.”  This  elevation  is  several  miles  in  length,  its  southern  extrem- 
ity being  two  miles  north  of  the  town ; the  constituent  rock  strata  are 
of.  Chester  age  below,  passing  upward  into  the  Mansfield  sandstone  and 
conglomerate  of  the  Pennsylvanian.  Just  northwest  of  the  town, 
along  the  river  bank,  is  the  long  narrow  ridge  known  as  the  “Devirs 
Back  Bone,”  which  is  entirely  of  Devonian  rocks.  Northeast  of  the 
town  is  the  third  elevation  which  is  much  broader  and  less  abrupt  than 
the  “Back  Bone;”  at  its  southern  extremity  the  rocks  are  of  Devonian 
age,  but  at  its  northern  end  they  are  Mississippian  limestones.  In  the 
extreme  northern  part  of  this  hill  a quarry  known  as  the  “City  Quarry” 
has  been  opened  in  which  the  Salem  and  St.  Louis  limestones  are  ex- 
posed. The  beds  at  this  point  dip  to  the  northeast  at  an  angle  of  about 
24  degrees  so  that  the  lower  strata  are  exposed  in  the  southwestern 
part  of  the  quarry.  Certain  of  these  low’er  beds  exhibit  features  which 
are  highly  characteristic  of  the  Salem  limestone  elsewhere,  with  the 
typical  Spergen  Hill  fauna  represented  by  an  abundance  of  both  spec- 
ies and  individuals.  The  dividing  line  between  the  Salem  and  the  St. 
Louis  is  not  so  distinctly  shown  here  as  in  Monroe  county,  but  the 
lower  beds  in  the  quarry  are  none  the  less  distinctly  Salem  limestone. 

Union  county — The  stratigraphy  of  the  Mississippian  formations  in 
Union  county  was  misinterpreted  by  Worthen  because  of  his  failure 
to  recognize  the  extensive  faulting  of  the  strata  which  has  taken  place 
in  the  southern  part  of  the  State.  In  the  east  and  west  section  passing 
through  Jonesboro  and  Anna  he  recognized  a succession  of  higher 
and  higher  beds  passing  from  the  Devonian  black  shale  through  the 
Mississippian  series  in  regular  succession,  except  that  the  St. 
Louis  limestone  was  believed  to  follow  immediately  after  the  sup- 
posed Kinderhook  shales,  the  limestone  ^ along  Swan  creek, 
east  of  Anna,  being  considered  as  the  upper  beds  of  the 
St.  Louis*.  A reconnaissance  survey  of  this  part  of  the 
State  by  the  writer  has  shown  that  the  structural  features  are  by 
no  means  so  simple  as  Worthen’s  interpretation  would  indicate.  The 
succession  of  the  beds  is  perfectly  normal  through  ■ the  Kinderhook, 
Burlington,  Keokuk-Warsaw,  Salem  and  St.  Louis,  but  their  relations 
have  been  obscured  by  faulting.  A fault  with  a general  north-south 
direction  seems  to  pass  along  Swan  creek  with  the  upthrow  on  the  east, 
so  that  the  supposed  upper  St.  Louis  beds  of  Worthen  appear  to  be  the 
Salem  limestone.  The  fauna  of  the  limestone  exposed  in  the  old 
quarries  along  Swan  creek  is  nearly  the  typical  Spergeq  Hill  fauna, 
and  this  occurrence  of  the  fauna  in  beds  supposed  to  be 
upper  St.  Louis  is  perhaps  one  of  the  facts  which  led  Worthen  to 
combine  the  Salem  and  St.  Louis  limestones  in  one  formation.  The 

Surv..  111.,  vol.  3.  pp  41-44:  also  Econ.  Geol.  111.,  vol.  1.  pp.  48^1-487. 

-7  G S 


98 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


fauna  at  this  locality  has  some  features,  however,  which  suggest  that 
it  is  a representative  of  the  recurrent  Spergen  Hill  fauna  of  the  Ste. 
Genevieve  limestone  lying  above  the  St.  Louis.  The  true  relations  of 
the  beds  in  this  region  can  only  be  determined  by  more  detailed  study. 

In  its  lithologic  character  the  supposed  Salem  limestone  of  Union 
county  resembles  the  same  formation  elsewhere  except  that  some  of  the 
beds  are  more  cherty  than  is  usually  the  case  with  the  formation.  The 
survey  of  the  region  has  not  yet  been  carried  far  enough  to  determine 
the  extent  of  the  formation  in  the  county,  and  as  yet  it  has  only 
been  observed  along  Swan  creek,  where  it  is  represented  by  at  least 
100  feet  of  strata. 


Conclusion. 


The  Salem  limestone,  as  has  been  shown  in  the  preceding  pages,  is 
widely  distributed  in  Illinois,  from  Hancock  to  Union' counties,  al- 
though the  outcrops  of  the  formation  are  not  continuous  at  the  surface 
through  this  entire  area.  Its  lithologic  characters  are  more  or  less 
uniform  throughout  the  State  and  it  can  usually  be  differentiated  from 
the  superjacent  St.  Louis  limestone  without  difficulty.  The  faunal 
characters  of  the  formation  are  even  more  uniform  than  the  physical, 
and  are  identical  with  the  faunas  of  the  typical  expression  of  the  forma- 
tion in  Indiana..  These  beds  which  appear  at  intervals  along  the 
western  side  of  the  Illinois  coal  field,  are  doubtless  continuous  beneath 
it  across  the  entire  width  of  the  State  and  a part  of  Indiana,  coming  to 
the  surface  again  near  the  eastern  border  of  the  coal  field  in  the  latter 
State.  In  Indiana  the  formation  affords  one  of  the  most  valuable 
building  stones  of  America.  In  Illinois  it  is  apparently  not  usually  so 
well  adapted  for  such  purposes  as  in  Indiana,  either  because  of  the 
physical  characters  of  the  rock  itself  or  because  of  the  overlying 
heavy  beds  of  St.  Louis  limestone,  but  at  certain  localities  in  Monroe 
county  extensive  beds  could  probably  be  quarried  which  would  prove 
to  be  the  equal  of  the  Indiana  “Bedford  stone”  in  all  respects. 


Appendix. 


Preliminary  lists  of  species  in  the  Salem  limestone  faunules  col- 
lected in  Illinois. 


W.  56.  Warsaw,  Hancock  County.  (See  p.  85.) 


Rhipidomella  dubia  Hall. 
Spirifer  subaequalis  Hall. 
Fenestella  serratula  Ulr. 
Fenestella  multispinosa  Ulr. 


Rhombopora  sp. 

Cystodictya  lineata  Ulr. 
Worthenopora  spinosa  Ulr. 


W 92.  Near  Lock  Haven,  Madison  County.  (See  p.  91.) 


Fistulipora  sprrnenens^fi  Rom. 
Rhipidomella  dubia  Hall 
Orthothetes  minntus  Cum. 
Productus  Sp. 


Spirifer  subaequalis  Hall. 
Spirifer  lateralis  Hall. 
Sleminula  trinuclea  Hall. 


Wkller.  ] 


THE  SALEM  LIMESTONE. 


99 


W 93.  Near  Lock  Haven,  Madison  County. 


Endothyra  haileyi  Hall, 
Zaphrentis  spergenensis  Worthen. 
Zaphrentis  sp. 

Talarocrinus  simplex  Shum. 
Stenopora  sp. 

Fenestella  serratula  Ulr. 

Hemitrypa  prouti  Ulr. 

Hemitrypa  heedei  Cum.? 
Cystodictya  lineata  Ulr. 

W 94.  Riehl,s  Station, 

Fistulipora  spergenensis  Rom. 
Polypora  simulairix  Ulr.? 
Cystodictya  lineata  Ulr. 

Spirifer  hifurcatus  Hall. 

W 95.  Riehl’s  Station, 

Endothrya  haileyi  Hall. 

Zaphrentis  spergenensis  Worthen. 
Archaeocidaris  sp. 

Pentremites  conoideus  Hall. 
Rhombopora  bedfordensis  Cum.? 
Cystodictya  lineata  Ulr. 
Worthenopora  spatulata  (Prout). 
Orthothetes  minutus  Cum. 
Productus  biseriatus  Hall. 

Pugnax  grosvenori  Hall. 

Dielasma  formosa  Hall. 


(See  p.  91.) 

Worthenopora  spatulata  (Prout). 
Productus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 
Productus  indianensis  Hall. 
Camarophoria  subuneata  Hall. 
Dielasma  formosa  Hall. 

Spirifer  bifur catus  Hall. 

Spirifer  subcar diiformis  Hall. 


Madison  County.  (See  p.  92.) 

Spirifer  subaequalis  Hall. 
Spirifer  lateralis  Hall. 
Reticularia  pseudolineata  Hall. 
Platyceras  sp. 

Madison  County.  (See  p.  92.) 

Dielasma  turgida  Hall. 

Spirifer  bifurcatus  Hall. 
Spirifer  subaequalis  Hall. 
Eumetria  marcyi  (Shum.) 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 

Nuclua  shumardi  Hall. 
Microdon  oblongus  Hall. 
Straparollus  spergenensis  Hall. 
Holopea  proutana  Hall. 
Cladodus  sp. 

(See  p.  92.) 


W 96.  East  of  Riehl’s  Station,  Madison  County, 


Moniiopora  beecheri  Brab. 
Pentremites  conoideus  Hall. 
Fistulipora  spergenensis  Rom. 
Fenestella  tenax  Ulr. 


Orthothetes  minutus  Cum. 
Rhipidomella  dubia  Hall. 
Spirifer  bifurcatus  Hall. 
Reticularia  pseudolineata  Hall. 
Cliothyris  hirsuta  Hall. 


W 97.  East  at  Riehl’s  Station,  Madison  County.  (See  p.  92.) 

Rhipidomella  dubia  Hall.  Spirifer  lateralis  Hall. 

Productus  sp.  Seminula  trinculea  Hall. 


W 43.  Hull’s  Hollow,  Madison  County.  (See  p.  93.) 


Endothyra  baileyi  Hall. 
vaphrentis  cassedayi  E.  & H. 
Enallophyllum  grabaui  Green. 
Pentremites  koninckana  Hall. 
Poteriocrinus  sp. 

Talarocrinus  simplex  Shum. 
t:,pirorbis  annulatus  Hall. 
Fenestella  tenax  Ulr. 
Fenestella  exigua  Ulr. 
Hemitrypa  proutana  Ulr. 
Hemitrypa  nodosa  Ulr. 
Polypora  simulatrix  Ulr. 
Polypora  varsoviensis  (Prout). 


Olyptopora  sp. 

Orthothetes  minutus  Cum. 
Rhipidomella  dubia  Hall. 
Productus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 
Rhynchonella  wortheni  Hall. 
Rhynchonella  macra  Hall. 
Pugnax  grosvenori  AidiW. 
Dielasma  formosa  Hall. 
Dielasma  turgida  Hall. 
Spirifer  bifurcatus  Hall. 
Spirifer  subaequalis  Hall. 
Spirifer  subcar  dif  or  mis  Hall. 


ICX) 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


Spirferina  spinosa  N.  & P. 
Reticularia  setigera  Hall. 

Eumetria  marcyi  (.Shum.) 
tSeminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 

Nucula  shumardana  Hall. 

Conocar dium  catastomum  Hall. 
Conocardium  meekanum  Hall. 
Myalina  sp. 

Aviculopecten  sp. 

Ooniophora  plicata  Hall? 
Microdon  subellipticus  Hall. 
Microdon  ohlongus  Hall. 

Microdon  ellipticus  Whitf.? 
Cypricardinia  indtanensis  Hall. 
Dentalium  sp. 

Lepteopsis  levettei  (White). 

W 44.  Hull’s  Hollow, 
Zaphrentis  sp. 

Platycrinus  huntsvilliae  Troost. 
Fistulipora  spergenensis  Rom. 
Fenestella  serratula  Ulr.? 
Cystodictya  lineata  Ulr. 
Worthenopora  spatulata  (Prout., 
Orthothetes  minutus  Cum. 
Rhipidomella  duHa  Hall. 
Produccus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 
Camarophoria  subcuneata  Hall. 
Pugnax  grosvenori  Hall. 

Dielasma  formosa  Hall. 

W 45.  Hull’s  Hollow, 

Pentremites  conoideus  Hall. 
Productus  biseriatus  Hall. 

W 42.  Hopp  Hollow, 

Monilopora  beecheri  Grab. 
Fistulipora  spergenensis  Rom. 
Anisotrypa  fistulosa  Ulr.? 
Fenestella  tenax  Ulr. 

Fenestella  serratula  Ulr. 
Fenestella  multispinosa  Ulr. 
Hemitrypa  proutana  Ulr. 

Polypora  simulatrix  Ulr. 

Polypora  varsoviensis  Prout? 
Polypora  internodata  Cum. 
Polypora  spininodata  Ulr. 
Rhombopora  bedfordensis  Cum.? 
Cystodictya  lineata  Ulr. 

Proutella  discoidea  (Prout.) 
Worthenopora  spatulata  (Prout.) 
Orthothetes  minutus  Cum. 
Productus  altonensis  N.  & P. 


Pleurotomaria  humilis  Hall. 
Pleurotomaria  piasaensis  Hall. 
Pleurotomaria  meekana  Hall. 
Pleurotomaria  subglobosa  Hall. 
Pleurotomaria  (several  sp.) 
Bellerophon  sublaevis  Hall. 
Straparollus  spergenensis  (Hall). 
Murchisonia  vermicula  (Hall). 
Cyclonema  levenworthna  Hall. 
Naticopsis  carleyana  Hall. 
Bulimorpha  elongata  Hall. 
Holopea  proutana  Hall. 

Platyceras  acutirostris  Hall. 
Orthoceras  sp. 

Leper ditia  carbonaria  Hall. 
Phillipsia  sp. 


Madison  County.  (See  p.  93.) 

Dielasma  turgida  Hall. 

Spirifer  bifurcatus  Hall. 
Spirifer  subaequalis  Hall. 
Spirifer  subcar  diif  or  mis  Hall. 
Reticularia  setigera  Hall. 
Eumetria  marcyi  (Shum.) 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 
Conocardium  meekanum  Hall. 
Bellerophon  sublaevis  Hall. 
Straparollus  spergenensis  Hall. 
Holopea  proutana  Hall. 
Platyceras  circularis  Rowley. 

Madison  County.  (See  p.  92.) 
Reticularia  pseudolineata  Halt 


Madison  County..  (See  p.  93.) 

Productus  biseriatus  Hall. 
Productus  indianensis  Hall. 
Pugnax  grosvenori  Hall. 
Dielasma  formosa  Hall. 
Dielasma  turgida  Hall. 

Spirifer  bifurcatus  Hall. 
Spirifer  subaequalis  Hall. 
Spirifer  subardiiformis  Hall. 
Spiriferina  sp. 

Reticularia  pseudolineta  Hall. 
Eumetria  marcyi  (Shum.) 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 
Straparollus  spergenensis  Hall. 
Griffithides  sp. 

Phillipsia  sp. 


Wkllek.  ] 


THE  SALEM  LIMESTONE. 


lOl 


U 48.  Near  Columbia,  Monroe  County. 


Zaphrentis  spinulosa  E,  & H. 
Zaphrentis  sp. 

Amplexus  sp. 

Monilopora  beecheri  Grab. 

Pentremites  conoideus  Hall. 
Tricoelocrinus  obliquatus  Room. 
Metablastus  bipyramidatis  Hall. 
Synbathocrinus  swallovi  Hall? 
Batocrinus  irregularis  Casseday. 
Dichocrinus  oblongus  W.  & W. 
Talarocrinus  simplex  Shum. 
Archaeocidaris  sp. 

Stenopora  sp. 

Lioclema  punctata  (Hall). 

Fenestella  tenax  Ulr. 

Fenestella  compressa  Ulr. 

Fenestella  regalis  Ulr.? 

Polypora  biseriata  Ulr. 

Fenestralia  st.  ludovici  Prout. 
Rhombopora  bedfordensis  Cum. 
Cystodictya  lineata  Ulr. 

U 56. 

Zaphrentis  spergenensis  Worthen. 
Pentremites  conideus  Hall. 
Talarocrinus  simplex  Shum. 

Stenopora  sp. 

Fenestella  tenax  Ulr. 

Hemitrypa  proutana  Ulr. 
Rhombopora  bedfordensis  Cum. 
Cystodictya  lineata  Ulr. 

Cystodictya  ocellata  Ulr. 

W 236.  Near  Chalfin  Bridge, 

Orthothetes  minutus  Cum. 
Rhipidomella  dubia  Hall. 

Productus  altonensis  N.  & P. 

Pugnax  grosvenori  Hall. 

Spirifer  bifurcatus  Hall. 


(See  p.  95.) 

Worthenopora  spatulata  (Prout.) 
W orthenopora  spinosa  Ulr. 
Orthothetes  minutus  Cum. 
Rhipidomella  dubia  Hall. 
Productus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 
Strophalosiaf  sp. 

Pugnax  grosvenori  Hall. 

Dielasma  turgida  Hall. 

Spirifer  bifurcatus  Hall. 

Spirifer  subaequalis  Hall. 

Spirifer  subcar  diif  or  mis  Hall. 
Spiriferina  spinosa  N.  & P. 
Reticulari  apseudolineata  Hall. 
Eumetria  marcyi  (Shum.) 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 
Platyceras  acutirostris  Hall. 
Phillipsia  sp. 

Fish  teeth. 


(See  p.  95.) 

Worthenopora  spatulata  (Prout.) 
Productus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 
Dielasma  formosa  Hall. 

Spirifer  bifurcatus  Hall. 

Spirifer  subcar  diif  or  mis  Hall. 
Deltodus  sp. 

Cladodus  sp. 


Monroe  County.  (See  p.  95.) 

Reticularia  pseudolineata  Hall. 
Eumetria  marcyi  (Shum.). 
Seminula  trinuclea  Hall. 
Allorisma  sp. 

Deltodus  sp. 


1^2  Miles  South  of  Columbia,  Monroe  County. 


W 235.  Near  Brownsburg,  Monroe  County. 


Orthothetes  sp. 

Rhipidomella  dubia  Hall. 

W233.  Mississippi  River  Bluff, 

Zaphrentis  cassedayi  E.  & H. 
Fistulipora  spergenensis  Rom. 
Fenestella  sp. 

Cystodictya  sp. 

Orthothetes  minutus  Cum. 
Rhipidomella  dubia  Hall. 
Productus  altonensis  N.  & P. 
Productus  biseriatus  Hall. 

Pugnax  grosvenori  Hall. 

Dielasma  turgida  Hall. 

Spirifer  bifurcatus  Hall. 


Spirifer  subcardiiformis  Hall. 
Seminula  trinuclea  Hall. 


Spirifer  subcardiiformis  Hall. 
Reticularia  pseudolineata  Hall. 
Eumetria  marcyi  (Shum.). 
Athris  densa  H.  & C. 

Seminula  trinuclea  Hall. 
Macrodon  sp. 

Aviculopecten  sp. 

Bellerophon  sublaevis  Hall. 
Platyceras  acutirostris  Hall. 
Grifflthides  sp. 


Opposite  Renault  Station,  Monroe  Co. 


102 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


W 263.  Abandoned  Quarries,  Swan  Creek,  East  of  Anna,  Union  County. 


Endothyra  haileyi  Hall. 

Zaphrentis  spergenensis  Worthen? 
Zaphrentis  sp. 

Cystelasma  rugosum  Ulr.? 
Syringopora  sp. 

Palaeacis  cuneiformis  E.  & H. 
Pentremites  koninckana  Hall. 
Platycrinus  huntsvillae  Troost. 
Melonitesf  (plates). 

Rhipidomella  dubia  Hall. 
Productus  punctatus  Martin. 
Productus  cora  D’Orb. 
Camarophoria  wortheni  Hall. 
Dielasma  formosa  Hall. 

Dielasma  turgida  Hall. 

Reticularia  pseudolineata  Hall. 
Eumetria  marcyi  (Shum.) 


Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 

Nucula  shumardana  Hall. 
Aviculopecten  sp. 

GoniopTioraf  plicata  Hall. 
Dentalium  sp. 

Eotrochus  concavus  (Hall.) 
Bellerophon  sp. 

Bucanopsis  textiles  Hall. 
Straparollus  spergenensis  Hall. 
Strophostylus  carleyana  Hall. 
BulimorpJia  bulimiformis  Hall. 
Orthoceras  epigrus  Hall. 
GrifUthides  sp. 

Psammodus  sp. 

Gtenacanthus  sp. 


W.  264.  Outcrop  by  Roadside,  jSwan  Creek,  a Little  Less  Than  ^2  Mile 
North  of  Last  Locality,  Union  County. 


Orthothetes  sp. 
Productus  cora  D’Orb. 
Productus  sp. 

Dielasma  formosa  Hall. 
Dielasma  turgida  Hall. 
Spirifer  bifurcatus  Hall, 


Eumetria  marcyi  (Shum.). 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 
Aviculopecten  sp. 
Enchostoma  sp. 


W.  265.  Outcrop  by  Roadside,  Swan  Creek,  a Little  Less  Than  % Mile 
North  of  Last  Locality,  Union  County. 


Pentremites  konincki  Hall. 
Orthothetes  sp. 

Productus  sp. 

Dielasma  formosa  Hall. 
Dielasma  turgida  Hall. 
Spirifer  bifurcatus  Hall. 
Eumetria  marcyi  (Shum.) 
Seminula  trinuclea  Hall. 
Cliothyris  hirsuta  Hall. 


Nucula  shumardana  Hall. 
Nucula  sp. 

Goniophora?  plicata  Hall. 
Lepetopsis  sp. 

Bembexia  elegantula  (Hall)? 
Porcellia  sp. 

Strophostylus  carleyana  Hall. 
GrifUthides  sp. 


LOWER  PALEOZOIC  STRATIGRAPHY  OF  SOUTH- 
WESTERN ILLINOIS  * 

(By  T.  E.  Savage.) 


Contents. 

Page 

Introduction  104 

Earlier  geological  work 104 

Composite  section  of  the  Pre-Mississippian 105 

Ordovician  109 

Galena-Trenton  109 

Richmond-Maquoketa  no 

Middle  Silurian 110 

Alexandrian  110 

Silurian  ■ • Ill 

Clinton  Ill 

Devonian  112 

Helderhergian  112 

Oriskanian  113 

Onondaga  113 

Hamilton  • • . . . 114 

Upper  Devonian 115 

Conclusion  115 


* Previously  published  in  briefer  form  in  the  American  Journal  of  Science,  May,  1908 


104 


YEAR  BOOK  FOR  I907. 


[Bor.L.  No.  8 


Introduction. 

The  following  paper  is  a preliminary  statement  concerning  the  pre- 
Mississippian  formations  that  occur  in  the  southwest  portion  of  Illinois. 
A detailed  report  on  the  stratigraphy  and  paleontology  of  these  ter- 
ranes  in  the  above  mentioned  area  is  in  preparation  by  the  writer.  The 
field  work  on  which  the  report  is  based  was  done  during  the  summer 
of  1907,  under  the  auspices  of  the  Illinois  Geological  Survey ; while 
the  paleontological  study  was  made  at  the  Peabody  Museum,  Yale 
University,  under  the  direction  of  Professor  Charles  Schuchert.  To 
the  latter  the  writer  wishes  to  acknowledge  his  indebtedness  for  valu- 
able assistance  in  the  study  and  interpretation  of  the  faunas  and  the 
data  that  were  collected. 

The  pre-Mississippian  beds  in  this  portion  of  the  State  underlie 
the  surficial  materials  over  an  area  150  miles  in  extent.  They  appear 
in  the  southwest  corner  of  Jackson  county  in  the  Back  Bone  and  Bake 
Oven  ridge,  at  the  south  end  of  Walker  ridge,  and  at  Bald  Rock  and 
southward  on  the  east  side  of  Big  Muddy  river.  In  Union  and  Alex- 
ander counties  they  extend  from  the  flood-plain  of  the  Mississippi  east- 
ward to  a general  line  passing  within  about  one  mile  west  of  the  towns 
of  Alto  Pass,  Mountain  Glen,  Jonesboro  and  Mill  Creek,  to  a point 
nearly  two  and  one-half  miles  southeast  of  Elco,  whence  the  line  sep- 
arating the  Devonian  from  the  younger  formations  trends  toward  the 
southwest  past  the  Diswood  postoffice,  to  near  the  middle  of  section  28, 
T.  15  S.,  R.  2 W.  Eastward  they  are  bordered  by  Mississippian  beds, 
while  along  the  southern  edge  sands  and  clays  of  Tertiary  age  lie  upon 
the  flanks  of  these  older  formations.  Occasional  patches  of  Tertiary 
gravels  occur  within  the  region  under  discussion. 

This  small  area  is  exceedingly  interesting  geologically  because  of 
the  fact  that  some  of  the  formations  here  represented  do  not  appear 
further  north  anywhere  in  the  Mississippi  valley.  The  successive  beds 
were  deposited  in  a basin  of  the  Interior  or  Mississippian  sea  which, 
during  a great  part  of  the  time,  was  more  or  less  separated  from  that 
in  which  the  older  strata  in  other  portions  of  the  State  were  laid  down. 
Owing  to  its  proximity  to  Ozarkia  this  basin  was  subjected  to  vertical 
movements  and  therefore  to  variable  conditions  of  sedimentation,  very 
different  from  those  that  prevailed  during  the  same  time  over  the 
more  northern  areas. 


Earlier  Geological  Work. 

In  volume  III  of  the  Geological  Survey  of  Illinois,  Professor  Wor- 
then  published  reports  on  the  geology  of  Jackson,  Union  and  Alexan- 
der counties  in  which  he  describes,  in  a general  way,  the  stratigraphy 
of  the  region  under  discussion.  In  1897  Dr.  Weller*  published  a list 
of  fossils  collected  at  the  Bake  Oven,  in  Jackson  county,  with  a discus- 
sion of  the  relations  of  these  to  the  Middle  Devonian  faunas  of  other 
localities. 

♦“WellerT  Jour.  Geol.,  vol.  5,  pp.  625-635.  1897. 


Savage.]  PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS.  I05 

No  careful  detailed  study  of  the  lower  Paleozoic  beds  of  this  region 
as  a whole  has  ever  been  attempted  previous  to  the  present  work. 
This  neglect  was  doubtless  due,  in  part,  to  the  small  size  of  the  area ; 
to  the  absence  of  the  more  important  economic  deposits ; and  to  the 
fact  that  the  deformations  and  unconformities  occuring  in  this  region 
have  made  the  geological  relations  of  the  beds  obscure ; and  that  many 
of  the  formations  present  here  cannot  be  correlated  with  those  in  other 
portions  of  the  State. 

Composite  Section  of  the  Pre-Mississippian  Strata  Occurring  in 
Southwestern  Illinois. 

The  general  relations  of  the  Lower  Paleozoic  formations  in  south- 
western Illinois  may  be  represented  in  a generalized  section  as  follows : 


S 


D 


(O 


o 

> 

H 

Q 


Correlations. 


Location 

of 

sections. 


Descriptions  of  horizons. 


<u 

Q 


a> 

O. 

P. 


L) 


© 


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^ "ci  o "eS  "ci 
^£3  0.0 ja 
©cfl  acCc/} 
IZ 


a 

o3 

a 


I 

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'S  e4  a c h 3 


10c.  Greenish-blue  shale,  fossils  almost  none — 
29  ft. 

10b.  Black  shale  with  few  fossils,  hut  carrying 
numerous  very  small  balls  of  iron  pyrite 
from  % to  % inch  in  diameter — 21  ft. 

10a  Brown  to  black,  siliceous  shale  or  shaly 
limestone  with  Leiorhjmchus  plohuli- 
formis  and  Reticularia  laevis — 36%  ft. 


9c. 


9b. 

9a, 


:<!•»  a 

vS  o 


© .0  , 

M c/i  t-* 


8a. 


Light  gray  siliceous  limestone,  in  part 
oolitic,  characterized  hyChonetes  cor- 
onatus,  Granaena  romingeri,  Spirifer 
pennatus,  8.  audaculus,  Tropidoleptus 
carinatus  and  Vitulina  pustulosa — 7 ft. 
Yellowish-brown  siliceous  or  shaly  lime- 
stone with  few  fossils — 25  ft 
In  the  north  are  dark  colored,  fine  grained 
limestones  with  Microcyclus  discus, 
Chonetes  yandellanus,  Eunella  attenicata, 
Parazyga  hirsuta,  Spirifer  fornacula  and 
8.  pennatus.  In  the  south  are  gray  or 
leached  limestones  with  A thyris  spiri- 
feroides.  Delthyris  sculptilis,  Spirifer 
granulosus,  Rhipidomella  penelope — 38 


Rather  soft  shale  weathering  to  a yellow- 
ish-brown color,  with  Leiorhynchus  limi- 
tare — 28  ft. 


This  horizon  is  not  present  at  the 
north  in  Jackson  county. 


The  Onondaga  is  well  developed  in 
Jackson  county  where  it  passes  without 
a break  into  the  Hamilton.  In  the 
southern  part  of  Union  county  there  is 
a break,  and  the  Onondoga  is  represented 
only  by  the  basal  sandstone,  7a  of  sec- 


io6 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


Composite  Section  of  the  Pre-Mississippian  Strata — Continued. 


Correlations. 


Location 

of 

sections. 


Descriptions  of  horizons. 


7L  Heavy  layers  of  very  hard,  gray,  coarsely 

crystaline  limestone ; containing  corals, 
Ghonetes  konickianus,  Pholidostrophia 
iowensis,  Productella  spinulicosta  and 
Stropheodonta  concava.  Strophalosia 
truncata  is  ahundont  in  the  lower  half, 
while  Productella  spinulicosta  is  common 
in  the  upper  part — 26ft. 

7h.  Layer  of  dark  colored  limestone  largely 
composed  of  shells  of  Ghonetes  konicki- 
anus  var. — ^^3  5-6  ft. 

7g.  Thin  bedded,  hard,  gray  limestone,  layers 

2-10  inches  thick.  Fossils  rare,  Ghon- 
etes konickianus  var.  common  in  the 
upper  part  and  G.  pusillus  with  Stopheo- 
donta  concava  in  the  lower — 15  ft. 

7f.  Hard,  gray,  impure  limestone  with  few 

fossils — 21  ft. 


O 

> 

w 

Q 


(U 

•a 


7e.  Dark  gray,  impure  limestone  with  thin 
chert  bands  near  the  top.  Fossils  numer- 
ous, Nucleocrinus  verneuili,  Rhynchonella 
gainesij  Meristella  harrisi,  Spirifer  acum- 
inatum, Stropheodonta  patersoni,  etc. — 
SVs  ft. 

7d.  Dark  gray,  impure,  fine-grained  limestone. 
Ghonetes  mucronatus  abundant  in  a zone 
near  the  middle.  Other  fossils  are  fthip- 
idomella  vanuxem,  Spirifer  qrieri, 
Stropheodonta  patersoni,  8.  perplana, 
and  Phacops  cristata — 11  ft. 

7c.  Heavy  layers  of  light  gray,  subcrystalline 
limestone.  Fossils  abundant.  Ooscinium 
crihriformis,  Gentronella  glansfagea, 
Spirifer  duodenarius,  8.  macrothyris  and 
Odontocephalus  aegeria  present  through- 
out— 38  ft. 

7h.  Alternating  iayers  of  light  gray,  arenac- 
eous, subcrystalline  limestone  and  coarse- 
grained sandstone,  containing  Gentron- 
ella glansfagea,  Meristella  near  lenti- 
formis,  Rhipidomella  cf.  musculosa,  Spir- 
ifer duodenarius  and  8.  macrothyris — 
15  y2  ft. 


S rSS  . 

“OP'S  “cwp  >> 

'I  N _ _i-r  cc  a 

IZi 


7a. 


Bed  of  more  or  less  iron-stained  sand- 
stone, in  places  soft  and  friable,  at  other 
points  cemented  by  a deposit  of  iron  or 
silica,  containing  Michelinia  stylopora, 
Aulacophyllum  sp.,  Gentronella  glans- 
fagea, Spirifer  duodenarius,  8.  macro- 
thyris and  Odontocephalus  arenarius — 
18  ft.  


New  Scotland,  about  158  feet.  | Upper  Oriskany— Clear  Creek  chert.  Camden  chert,  237  feet. 


S.WAGE.  ] 


PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS. 


107 


Composite  Section  of  the  Pre- Mississipian  Shata — Continued. 


Location 

Correlations. 

of 

sections. 

a 

: 

-(fu 

o 

. 

O CO  r. 
cs 


o 

_ l-J 


a 
,0 
5 o o 

> cop 


6e. 


6d. 


6c. 


Descriptions  of  horizons. 


Bed!  of  light  gray  chert  in  layers  .3-9  Inch- 
es thick,  Amphigenia  curia,  Chonostro- 
phia  reversa,  Eodevonaria  melonica, 
Schuchertella  pandora  and  Spirifer 
worthenanus  abundant — 5%  ft. 

Reddish-hrown,  friable  sandstone  with 
Michelinia  stylopora,  zaphrentis  sp., 
Amphigenia  curia  and  Spirifer  duodcnar- 
ius — 2 5-6  ft. 

Layers  of  light  gray  chert,  4-8  inches 
thick.  Anoplia  nucleaia,  Chonosirophia 
reversa,  Eodevonaria  melonica,  Schucher- 
iella  pandora  and  Spirifer  worihennnus 
— IVa  ft. 


a 

.2 

c 


c 

o 

‘S 


a 

o 

c 


^ 

eo  w 
P5  03 


6b. 

6a. 


^ cfi 


^ . 


a;> 
cc 

^ ^ ^ II,  ^ 

. a c G 

'Z  z 'Z 


Reddish-brown,  friable  sandstone — 2 ft. 

Bed  of  light  colored  chert  layers,  in  qlaces 
alternating  with  impure  siliceous  lime- 
stone, and  at  other  points  composed 
wholly  of  chert  bands.  Fossils  most 
abundant  in  the  upper  part.  Amphi- 
genia curias,  Anoploiheca  flahelliies,  Ea- 
ionia  peculia/ris,  Eodevona/ria  melonica, 
Chonosirophia  reversa,  Schuchertella 
pandora,  Spirifer  xvorihenanus,  and  S. 
hemicyclus  common  in  the  upper  part 
—225  ft. 

(In  the  southern  part  of  Union  county 
the  lower  chert  layers  are  massive  and 
contain  but  few  fossils.  In  the  pit 
worked  by  the  M.  & O.  railroad,  1% 
miles  north  of  Tamms,  in  Alexander 
county,  may  be  seen  an  exposure  of 
more  that  100  feet  in  which  few  fossils 
were  found.) 


A break  in  sedimentation. 


5b. 


Heavy  bedded,  light  colored,  coarsely  crys- 
talline limestone,  with  Eaionia  singu- 
laris,  Spirifer  macropleura,  S.  perlameU 
losus,  Siropheodonia  heckii,  and  Stroph- 
onella  punciuUfera — about  58  ft. 

Layers  of  impre,  shaly  limestone  alternat- 
ing with  bands  and  nodules  of  chert ; 
in  the  upper  portion  occur  Dalmanella 
suhcarinaia,  Merisiella  laevis,  Spirifer 
cyclopierus,  S.  perla/tnellosus  and  Sirop- 
honella  punciuUfera — 100  ft. 

(The  horizon  of  5a  appears  to  belong 
immediately  below  5b.  It  is  present  at 
Bald  Rock,  and  in  the  river  bluffs 
further  south,  but  the  fossils  were  not 
so  abundant  at  the  later  points.) 


lo8  YEAR  BOOK  FOR  I907.  [Bull.  No.  8 

Composite  Section  of  the  Pre-Mississippian  Strata — Continued. 


c 

Location 

c 

<v 

Correlations. 

of 

Descriptions  of  horizons. 

OD 

sections. 

CO 

A long  break  in  sedimentation. 

10 

^ «D 

4c.  Pink,  mottled  limestone,  in  layers  10-45 

inches  thick,  containing  many  small  im- 
mature brachiopods,  with  which  occur 
Plectamhonites  transversalis,  Raflnes- 
quina  mesacosta  and  Spirifer  near  sul- 
cata— 23  ft. 

4b.  Layers  of  gray  to  drab  colored  limestone. 
2-6  inches  thick,  alternating  with  thin 
bands  of  chert  and  characterized  by  such 
typical  Clinton  fossils  as  Stricklandinia 
triplcsiana  and  Triplecia  ortoni — 6 ft. 

4a.  Bed  of  tough,  grajr  limestone  in  layers  3-8 
inches  thick  which  are  imperfectly  sep- 
arated by  2 to  4-inch  partings  of  chert. 
Fossils  rare — •0-46  ft. 

(4a  is  wanting  at  some  points  in  this 
area. ) 


A break  in  deposition. 


3c.  Coarse-grained,  somewhat  oolitic  limestone, 
in  layers  12-18  inches  thick ; A trypa 
rugosa,  Rhynchotreta  sp.,  Schuchertella 
subplanus,  Whitfieldella  billingsana  and 
Lichas  breviceps  clintonensis  common — 
3 Vs  ft. 

3b.  Fine-grained,  dark  colored,  shaly  limestone, 
in  layers  4-10  inches  thick,  character- 
ized by  Rafinesquina  mesacosta,  Schu- 
chertella subplanus  and  Dalmanites 
danae — 2%  ft. 

3a.  Cape  Girardeau  limestone:  Fine-grained, 
black,  brittle  limestone,  layers  1-4  inches 
thick,  separated  from  each  other  by 
thin  lenses  or  partings  of  calcareous  shale 
on  the  surface  of  which  are  exposed 
cxinoids,  Rafinesquina  mesacosta,  Rhyn- 
chotrema  sp.,  Schuchertella  missouri- 
ensis  and  CornuUtes  tenuistriata — 33-38 
feet. 


A probable  short  break  in  sedimentation. 


O 


^2 

aiO 

D5§ 

Ho 

O 


2b.  Bed  of  grayish-blue  shale  in  which  1-inch 
bands  of  more  resistant  calcareous  shale 
occur  4-6  inches  apart,  bearing  Rhyn- 
chotrema  inaequivalvef,  Strophomena 
sulcata?  Zygospira  recurvirostra,  Conra- 
della  sp.  and  Isotelus  sp.  not  rare — 18  ft. 

2a.  Thebes  sandstone  and  shale:  Bluish  to 
brown,  shaly  sandstone  in  layers  % to 
2%  feet  thick;  the  upper  prtion  thin- 
ner bedded  with  a larger  admixture  of 
shale.  Lingula  cf.  covingtonensis  the 
only  fossil  found  in  the  upper  part, 
while  Isotelus  sp.,  occurs  near  the  base — 
73  ft. 


Savage.  J 


PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS. 


109 


Composite  Section  of.  the  Pre-Mississippian  Concluded. 


a 

Location 

Correlations. 

of 

Descriptions  of  horizons. 

cn 

sections. 

>. 

03 

A break  in  Deposition. 


g 

a . 

ob 

CO 

■d 

s 

,d 

o 

sa  . . 

a 

A 

o 

a 

® 

fl  s" 

s 

^ . 
fl 

- 

0 

H 

% . 
<% 

030 

HO 

Is 


la. 


Light  gray,  coarsely  crystalline  limestone^ 
in  regular  layers  3-48  inches  thick  ; the 
upper  part  characterized  hy  the  fossils 
Receptaculites  oweni,  Eeberteila  near 
occidentalis,  Platpstrophia  bifnrata, 
Plectorthis  plicatella,  Cytolites  ornatu» 
and  Platymetoous  cucullus ; while  the 
lower  portion  is  marked  by  Receptacul- 
ites oweni,  Rhynchotrema  inaequivalve, 
Parastrophia  hemiplicaa  and  Triplecia 
sp.— 68-80  ft. 


Ordovician. 

Galena-Trenton — A thickness  of  68  to  8o  feet  of  this  formation  is 
exposed  in  Alexander  county.  It  appears  at  two  points  adjacent  to  the 
Mississippi  river  where  the  waters  of  that  stream  have  cut  across  low 
arches  which  bring  the  Galena  limestone  above  the  level  of  the  water. 
One  of  these  exposures  is  a short  distance  below  Thebes,  where  a thick- 
ness of  about  68  feet  of  the  limestone  may  be  studied.  The  second 
fold  crosses  the  river  about  two  miles  north  of  Thebes,  a short  distance 
west  of  the  village  of  Gale,  where  the  limestones  may  again  be  seen 
on  Little  Rock  Island. 

The  Galena  formation  is  here  a light  colored,  crystalline,  non-mag- 
nesian  limestone,  in  layers  from  a few  inches  to  four  feet  in  thickness, 
which  is  imperfectly  exposed  in  the  upper  part.  The  lowest  layers 
contain  in  abundance,  Receptaculites  oweni,  Hpbertella  near  occiden- 
talis, Parastrophia  hemiplicata,  Platystrophia  biforata,  Rafinesquina 
alternata,  Rhynchotrema  inaequivalve,  Strophomena  emaciata,  Trip- 
lecia n.  sp.,  and  the  trilobites  Bronteus  lunatus,  Bumastus  trentonensis, 
Illaenus  americanus,  Isotelus  maximus,  'and  Platymetopus  cucullus. 
Eighteen  feet  above  low  water  Crania  trentonensis,  Cyrtolites  ornatus, 
Plectorthis  plicatella  and  Remopleurites  striatulus  are  assosiated  with 
most  of  the  above  mentioned  forms.  In  the  middle  and  upper  parts 
the  white  color  is  in  places  mottled  with  pink,  and  the  fossils  become 
much  less  abundant.  Receptaculites  oweni  is  still  common  while  Crania 
trentonensis,  Hebertella  near  occidentalis,  Platystrophia  biforata, 
Rafinesquina  alternata,  Rhynchotrema  inaequivalve  and  Triplecia  n.  sp. 
persist  in  diminished  numbers. 

This  facies  of  the  Galena  resembles,  in  its  fossils  and  lithology,  the, 
Kimmswick  limestone  of  Ulrich,  also  described  by  Weller  from  Jersey 
and  Calhoun  counties.*  The  basin  in  which  it  was  deposited  was 
probably  somewhat  separated  from  that  which  received  the  sediments 
of  the  more  northern  dolomite  phase  of  the  Galena. 

♦Weller:  Illinois  State  Geol  Surv.,  Bull.  No. '4.  p.  222. 


no 


YEAR  BOOK  FOR  1 90/. 


[Bull.  No.  8 


Richmond-M aquoketa — The  beds  that  belong  to  the  Richmond  for- 
mation have  an  aggregate  thickness  of  91  feet.  This  formation  suc- 
ceeded that  of  the  Galena  after  a long  landi  interval.  All  of  the  Utica 
and  I.orraine  deposits  are  wanting,  and  seemingly  much  of  the  Rich- 
mond is  also  absent.  The  formation  in  southwest  Illinois  consists  of 
two  members,  2a  and  2b  of  the  general  section.  The  lower  one  (2a) 
is  a sandstone  or  sandy  shale — “Thebes  sandstone  and  shale” — which 
is  exposed  along  the  flanks  of  the  Thebes  and  Gale  anticlines,  and  in 
the  intervening  trough.  The  materials  are  reddish  brown  where  weath- 
ered, and  blue  where  not  changed  by  the  atmosphere.  The  lower  part 
is  a sandstone,  thick  bedded  and  in  regular  Jayers,  which  is  well  ex- 
posed at  the  east  end  of  the  railroad  bridge  at  Thebes.  In  the  upper 
half  the  layers  are  thinner  and,  where  much  weathered,  appear  de- 
cidedly argillaceous.  This  more  shaly  horizon  is  well  exposed  in  the 
river  bank  three-fourths  of  a mile  south  of  Gale.  Lingula  cf.  coving- 
tonensis  occurs  sparingly  throughout  the  sandy  shale  of  this  member. 

The  upper  member  is  a bed  of  fossiliferous,  bluish  shale  (2b  of  the 
section.)  It  is  exposed  in  the  bank  of  the  river  and  in  a cut  along  the 
Illinois  Central  railway  about  three-fourths  of  a mile  south  of  Gale, 
where  it  overlies  the  “Thebes  sandstone  and  shale”  member.  The  bed 
has  a thickness  of  18  ft.,  and  contains  Cyclocystoides  n.  sp.,  Phylloporina 
near  granistriata,  Dalmanella  testudinaria,  Plectambonites  sericea, 
Rhynchotrema  inaequivalve? , Strophomena  stdcataf,  ::ygospira  recuru- 
irostra,  Conradella  near  dmhriata,  and  species  of  Isofelus  resembling 
/.  susae  and  /.  platycephcilus.  The. lithologic  and  faunal  change  from 
the  Thebes  sandstone  member  to  this  blue  shale  is  abrupt,  which  may 
indicate  a break  between  the  two  beds.  The  fauna  reminds  one  much 
of  the  Black  river  formation,  but  as  it  occurs  above  the  Rhynchotrema 
cap  ax  zones  in  Missouri,  and  its  life  assemblage  is  not  at  all  that  of  the 
overlying  Cape  Girardeau  limestone,  it  must  belong  in  the  Richmond 
with  the  Thebes  sandstone. 

Neither  of  these  members  contain  Rhynchotrema  capax,  the  widely 
distributed  guide  fossil  to  the  Richmond.  However,  across  the  river, 
in  the  vicinity  of  Cape  Girardeau,  Mo.,  were  found  thin  layers  of  gray, 
sub-crystalline  limestone,  5-7  feet  thick,  which  contain  Rhynchotrema 
capax  and  other  Richmond  'fossils  in  abundance.  This  zone  occurrs 
just  above  the  white,  heavy-bedded  Galena  limestone,  and  immediately 
below  the  Thebes  sandstone.  The  same  limestone  horizon,  bearing 
R.  capax,  is  doubtless  present  in  Ilinois,  but  the  contact  between  the 
Galena  and  the  Richmond  formations  was  nowhere  found  exposed. 

The  above  shales  and  sandstone  do  not  extend  so  far  north  as  does 
the  underlaying  limestone.  The  sea  in  which  they  were  deposited  prob- 
ably washed  the  shores  of  the  O'zarkian  land  area  a few  miles  to  the 
west  which,  during  late  Richmond  time,  was  the  source  of  the  sedi- 
ments that  make  up  these  terrigenous  beds. 

Middle  Silurian. 

Alexandrian — The  beds  referred  to  this  formation  are  exposed  in 
Alexander  county  to  a thickness  of  44  feet.  They  include  the  Cape 
Girardeau  limestone  and  the  overlying  beds  containing  Dalmanites  danae 
and  Whitheldella  hillingsana.  The  Cape  Girardeau  limestone  is  well 


Savage.  ] 


PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS. 


Ill 


exposed  about  two  miles  south  of  Thebes,  in  the  bank  of  the  river  and 
along  the  streams  in  that  immediate  vicinity.  It  is  also  seen  in  a cut 
along  the  Illinois  Central  railroad  and  in  the  river’s  bank  one  and 'one- 
half  miles  north  of  Thebes.  In  the  former  locality  this  member  is  near- 
ly 40  feet  thick,  and  consists  of  black,  fine  grained,  brittle  limestone,  in 
thin  layers  which  are  often  separated  by  narrow  partings  of  dark, 
calcareous  shale.  This  zone  has  a rich  fauna  that  appears  abruptly  at 
this  horizon.  Among  the  forms  are  several  species  of  crinoids,  Dal- 
manella  near  elegantula,  Homoeospira  n.  sp.,  Leptaena  rhomhoidalis, 
Raiinesquina  mesacosta,  Rhynchotreta  n.  sp.,  Schuchertella  missourien- 
sis,  Zygospira  n.  sp.,  Cormilites  tenuistriata,  C.  incurvus,  Platyostoma 
near  niagarensis,  Strophostylus  sp.,  Acidaspis  halli,  Calymene  sp., 
Cyphaspis  girardeauensis  and  Encrinurus  sp. 

At  the  exposure  north  of  Thebes  the  Cape  Girardeau  limestone  rests 
directly  upon  the  fossiliferous  blue  shale  (2b  of  section).  This  mem- 
ber is  succeeded  by  a bed  of  dark  gray  limestone,  oolitic  in  the  upper 
part,  which  contains  Favosites  sp.,  Stromatopora  sp.,  Atrypa  rugosa, 
Clorinda  n.  sp.,  Homoeospira  n.  sp.,  cf  Hindeila  umhonata,  Leptaena 
rhomboidalis,  Platystrophia  biforata,  Raiinesquina  mesacosta,  Rhy- 
nchotreta n.  sp.,  Schuchertella  subplanus,  (probably  a coarse  form  of 
♦S',  missouriensis)  Strophomena  sp.,  Whitheldella  billingsana,  Dalman- 
ites  danae,  Dalmanites  sp.,  and  Lichas  breviceps  clintonensis. 

There  are  here  no  diagnostic  fossils  of  the  Richmond.  The  genera 
Favosites,  Stromatopora,  Atrypa,  Whitdeldella,  Homoeospira,  Schu- 
ehertella  and  Clorinda  do  not  occur  in  American  Ordovician  strata, 
while  Atrypa  rugosa  and  Lichas  breviceps  clintonensis  are  found  in  the 
Silurian.  On  the  other  hand  the  fauna  is  not  directly  related  to  that 
of  the  Clinton,  from  which  formation  it  is  separated  by  a marked 
, erosional  unconformity.  Schuchert  cites*  a fauna  from  Edgewood  in 
eastern  Missouri,  collected  by  Ulrich,  which  corresponds  closely  with 
the  above.  Since  there  seems  to  be  no  direct  time  equivalent  of  these 
beds  in  the  Ordovician  or  in  the  Silurian,  as  generally  defined,  the  hori- 
zons 3a  to  3c  are  classed  as  Middle  Silurian  strata  that  more  or  less 
completely  bridge  the  lost  interval  between  the  Cincinnation  and  the 
Clinton.  For  these  beds  the  time  term  Alexandrian  is  proposed,  from 
Alexander  county,  Illinois,  where  they  are  well  exposed;  the  term  to 
have  the  same  rank  as  Cincinnatian,  which  it  immediately  follows. 

Silurian. 

Clinton — The  limestone  of  this  formation  has  here  a maximum  thick- 
ness of  75  feet.  One-half  mile  southeast  of  Gale  it  immediately  overlies 
the  shale  member  (2d  of  section)  above  the  Thebes  sandstone, 
all  of  the  Alexandrian  beds  having  been  cut  out  by  erosion  prior 
to  the  deposition  of  the  Clinton.  One  and  one-half  miles  north  of 
Thebes  the  Clinton  limestone  rests  on  the  Whitdeldella  billingsana  zone 
(3c  of  section),  while  two  miles  south  of  Thebes  it  immediately  over- 
lies  the  Cape  Girardeau  limestone  (3a  of  section).  The  upper  part  of 
the  Clinton  (4c  of  section)  consists  of  heavy  bedded,  pink  or  mottled 


♦.Journal  of  Oeology.  Vol.  XIV,  pp.  728-729.'  1906. 


112 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


limestone,  23  feet  thick,  which  contains  many  small,  immature  brach- 
iopods  besides  Plectambonites  transversalis,  RaHnesquina  mesacosta, 
Spirifer  near  sulcata,  Illaenus  sp.,  and  a few  new  species  of  Orthoceras. 
Below  this  pink  limestone  lie  6 feet  of  thin  bedded,  dark  gray  limestone 
with  narrow  bands  of  chert  (4b  of  the  section).  The  limestone 
layers  contain  Favosites  favosus,  Haly sites  catenulatus,  Stromatopora 
sp.,  A try  pa  rugosa,  Orthis  cf  davidsoni,  Orthis  dabellites,  Plectam- 
bonites transversalis,  and  var.  elegantula,  Stricklandinia  triplesiana  and 
Triplecia  ortoni..  The  above  fauna  corresponds  with  that  of  the  In- 
terior or  Western  Clinton,  as  described  by  Foerste  from  the  region  of 
Dayton,  Ohio. 

The  lower  portion  of  this  formation  (4a)  is  well  exposed  in  the 
vicinity  of  Gale  and  two  miles  further  north  along  Sexton  creek,  in  the 
N.  W.  %.  of  sect.  27,  T.  14  S.,  R.  3 West,  where  it  consists  of  46  feet 
of  thin  bedded,  gray  limestone,  the  layers  of  which  are  separated  by 
narrow  chert  bands. 

The  thickness  of  the  Clinton  is  variable.  It  does  not  exceed  29  feet 
in  the  exposure  south  of  Thebes,  while  near  Gale,  and  along  Sexton 
creek  and  in  the  river  bluff  two  miles  east  of  McClure,  the  aggregate 
thickness  is  75  feet.  Where  the  formation  is  thinnest  it  is  the  lower 
and  not  the  upper  layers  that  are  absent. 

Devonian. 

Helderbergian — The  rocks  of  Helderbergian  age  in  Illinois  corre- 
spond with  the  New  Scotland  formation  of  New  York.  They  succeed 
the  Clinton  after  an  exceedingly  long  land  interval  represented  by  all 
of  the  Silurian  after  the  Clinton,  and  the  Coeymans  of  the  Lower 
Devonian.  In  New  Scotland  time  the  Interior  or  Mississippian  sea  was 
much  more  restricted  than  during  the  Clinton.  It  extended  as  an 
embayment  from  the  gulf  region  as  far  north  as  Jackson  county,  Illi- 
nois. It  spread  west  to  Oklahoma  and  east  as  far  as  southeast 
Tennessee.  It  was  separated  by  a land  barrier  from  the  Atlantic 
embayment ( Cumberland  basin)  which  occupied  parts  of  New  York, 
Maryland  and  northeastern  Tennessee;  and  it  is  probable  that  the 
Kankakee  barrier,  as  defined  by  Schuchert,  prevented  its  spreading 
far  to  the  north  and  northwest. 

The  New  Scotland  formation  in  Union  and  Jackson  counties  has 
an  aggregate  thickness  of  more  than  160  feet.  The  lower  portion, 
for  a thickness  of  100  feet,  consists  of  shaly  limestone  with  interbedded 
bands  of  chert.  This  phase  is  exposed  in  the  lower  part  of  Bald 
Rock,  four  miles  southeast  of  Grand  Tower  on  the  Big  Muddy  river. 
It  appears  in  the  east  bluflf  of  the  Mississippi  river  for  some  distance 
south  from  this  point.  It  makes  up  Tower  Rock,  in  the  Mississippi 
river  channel,  west  of  Grand  Tower,  and  it  is  exposed  on  the  Missouri 
side  of  the  river,  in  the  quarry  and  in  the  cut  made  by  the  Frisco 
railroad  company,  a short  distance  south  and  west  of  this  rock.  At 
the  latter  point  were  collected  Streptelasma  recta,  Dalmanella  sub- 
carinata,  Leptaena  rhomboidalis,  Leptaenisca  adnascens,  Meristella 
laevis,  Spirifer  cyclopterus,  S.  peramellosus,  Stropheodonta  punctuli- 
fera,  Hausmannia  sp.  and  Phacops  logani  var. 


Savage.]  PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS.  II3 

The  upper  58  feet  of  the  New  Scotland  formation  consists  of  light 
gray,  heavy  bedded,  coarsely  crystalline  limestone.  This  facies  is 
exposed  in  the  south  end  of  the  Back  Bone  ridge  where  a fault  brings 
it  above  the  level  of  the  flood  plain.  It  forms  the  upper  part  of  Bald 
Rock  where  another  fault  has  raised  it  to  the  level  of  the  adjacent 
Chester  limestone,  of  Mississippian  age.  It  occurs  in  the  east  bank  of 
Clear  creek  in  sections  23  and  24,  T.  ii  S.,  R.  3 West.  The  beds 
furnished  Aspidocrinus  scutellaeformis,  Anoplotheca  concava,  Eatonia 
singularis,  Leptaenisca  concava,  Megalanteris  condoni,  Meristella  arcu- 
ataf,  Oriskania  smuata  n.  var.,  Spirifer  concinnus,  S.  cyclopterus,  S. 
macropleura,  S.  perlamellosus,  Stropheodonta  beckii,  S.  varistriata, 
and  var.  arata,  Strophoella  punctulifera,  Uncinulus  nobilisf  and  U. 
nucleolata. 

Oriskanian  (Clear  Creek  cherts,  Camden  cherts) — The  Clear 
Creek  formation  consists  of  light  gray  to  yellowish  colored 
cherts  that  are  usually  in  thin  layers  but  which  in  the  lower  part  are 
sometimes  three  to  five  feet  in  thickness.  At  some  points  the  cherts 
are  thoroughly  leached  and  decomposed,  and  occur  as  a fine  white 
powder  that  can  be  dug  with  a shovel,  and  is  utilized  for  commercial 
purposes.  This  formation  rests  with  erosional  unconformity  upon 
the  New  Scotland  beds  at  the  south  end  of  the  Back  Bone  ridge.  Its 
fauna  corresponds  with  that  of  the  Camden  cherts  in  western  Ten- 
nessee. The  beds  represent  deposits  of  the  Upper  Oriskany  time,  as  is 
indicated  by  the  interwedging  of  the  upper  chert  layers  with  those 
of  the  basal  portion  of  the  succeeding  Onondaga  (see  6a  to  6e  of 
section).  The  chert  formation  has  a thickness  in  Illinois  of  about 
237  feet.  Fossils  are  somewhat  rare  in  the  lower  portion  but  in  the 
middle,  and  especially  in  the  upper,  part  there  is  a rich  fauna, 
including  Michelinia  n.  sp.,  Ambocoelia  cf.  umbonata,  Amphigenia 
curia,  Anoplia  nucleata,  Anoplotheca  dabellites,  A.  hmbriata,  Cen- 
tronella  glansfagea,  Chonostrophia  reversa,  Cyrtina  hamiltonensis, 
Eatonia  peculiaris,  E.  cf.  whitheldi,  Eodevonaria  melonica,  Stropheo- 
donta per  plana,  Megalanteris  condoni,  Oriskania  sinuata,  n.  var., 
Pholidops  terminalis,  Rhipidomella  musculosa,  Spirifer  worthenanus, 
S.  duodenarius,  S.  macrothyris,  S.  hemicyclus,  S.  tribulis,  S.  cf.  mur- 
chisoni,  Schuchertella  pandora,  Acidaspis  tuberculata,  Odontocephalus 
arenarius  and  Phacops  cristata. 

These  upper  Oriskany  beds  were  deposited  near  the  north  end  of 
the  Mississippian  embayment  which  at  this  time  was  even  more  con- 
tracted than  during  the  Helderbergian.  The  basin  was  remote  from, 
and  not  connected  with,  the  NewYork-Maryland  province  (Cumber- 
land basin).  It  covered  western  Kentucky  and  Tennessee,  and  lapped 
over  the  southeast  corner  of  Missouri  and  the  east  side  of  Arkansas, 
spreading  an  arm  across  northern  Alabama. 

Onondaga — The  sedimentation  of  the  Upper  Oriskany  time  con- 
tinued without  a break  into  the  Onondaga  or  Corniferous.  The  latter 
period  was  initiated  by  disturbances  to  the  westward,  in  Ozarkia, 
which  increased  mechanical  sedimentation  in  the  Illinois  area.  These 
resulted  for  a time  in  the  deposition,  along  the  eastern  shore  of 
Ozarkia,  of  layers  of  sand  containing  Onondaga  fossils  alternating 

— 8 G S 


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[Bull.  No.  8 


II4 


with  the  return  of  the  Oriskanian  limestone  conditions.  Eventually 
sand  deposition  prevailed  and  there  was  spread  over  the  region  the 
basal  sandstone  of  the  Onondaga  formation  (ya  of  section),  contain- 
ing Michelinia  stylopora,  Aulacophylluni  sp.,  Amphigenia  curta,  Cen- 
tronclla  glansfagea,  Meristclla  near  lentiformis,  Rhipidomella  muscu- 
losa,  Spirifer  duo  denarius,  S.  macrothyris , Conocardium  cuneus  and 
Odontocephalus  arenarius. 

Early  in  Onondaga  time  an  elevation  in  the  southern  portion  of 
Union  and  in  Alexander  county  put  a stop  to  further  deposition  in 
that  locality,  while  farther  north,  in  Jackson  county,  sedimentation 
was  uninterrupted. 

At  the  cut  through  the  Back  Bone  and  at  the  Bake  Oven,  a short 
distance  north  of  Grand  Tower,  there  is  exposed  a continuous  section 
of  the  Onondaga  formation  showing  a thickness  of  115  feet.  The 
beds  consist  largely  of  light  colored,  regularly  bedded,  more  or  less 
crystalline  limestone  which  becomes  arenaceous  in  the  lower  part. 
Fossils  are  abundant  throughout  the  section. 

The  upper  layers  are  marked  by  Chonetes  konickanus,  Leptaena 
rhomboidalis,  Pentamerella  arata,  P.  papilionensis,  Meristella  rostrata, 
Rhynchonella  gainesi,  Spirifer  acuminatus,  S.  grieri,  S.  macra,  Stro- 
pheodonta  patersoni,  Conocardium  trigonale  and  Onychodus  sigmoides. 
In  the  lower  part  Nucleocrinus  verneuili,  Coscinium  cribriformis,  Cen- 
tronella  glansfagea,  Leptaena  rhomboidalis,  Meristella  barrki,  Pen- 
tamerella arata,  Spirifer  acuminatus , S.  duodenarius,  S.  macrothyris, 
Stropheodonta  patersoni,  Dalmanites  calypso,  Odontocephalus  aegcria 
and  Onychodus  sigmoides  are  common. 

During  the  Onondaga  and  the  succeeding  Hamilton  time  the  warm 
waters  from  the  gulf  region,  with  their  successive  faunas,  spread 
towards  the  northeast  across  Illinois  and  Indiana,  passing  around  the 
north  end  of  the  Cincinnati  axis,  and  mingled  with  those  of  the 
eastern  embayment  in  western  New  York.  Such  water  connections 
permitted  free  migrations  within  this  sea,  and  explains  the  close  corre- 
spondence between  the  various  Middle  Devonian  faunas  of  south- 
western Illinois  and  those  of  western  Ontario  and  New  York. 

Hamilton — Throughout  Hamilton  time  the  Kankakee  barrier  or 
peninsula,  extending  from  Ozarkia  towards  the  northeast  across  Illi- 
nois, was  largely  effective  in  preventing  the  waters  of  the  Interior 
or  Mississippian  sea  from  uniting  with  those  of  the  Northwestern 
or  Dakotan  basin  towards  the  northwest.  As  a result  of  this  separa- 
tion the  deposits  and  the  faunas  of  Hamilton  time,  in  Illinois,  belong 
to  two  distinct  provinces.  The  phase  of  the  Hamilton  in  the  vicinity 
of  Rock  Island,  and  in  Jersey  and  Calhoun  counties,  belongs  to  the 
Northwestern  or  Dakotan  province  ; while  that  of  the  southwest  Illi- 
nois belongs  to  the  New  York  province. 

The  New  York  faunal  phase  of  the  Hamilton  is  well  developed  in 
the  south  part  of  Union  county,  in  the  north  half  of  sect.  34,  T.  13  S., 
R.  2 West,  and  further  north  in  the  N.  E.  of  sect.  34,  T.  ii  S., 
R.  2 West.  The  formation  is  also  represented  by  the  upper  beds  near 
the  north  end  of  Back  Bone  ridge,  in  Jackson  county. 


Savage.]  PALEOZOIC  OF  SOUTHWESTERN  ILLINOIS.  II5 

At  the  first  mentioned  exposure  there  is  at  the  base  of  the  Hamilton 
28  feet  of  yellowish-blue  shale  which  contains  Leiorhynchus  limitare, 
both  the  character  of  the  sediment  and  the  fossils  reminding  decidedly 
of  the  Marcellus  shale  of  New  York.  This  shale  rests  unconformably 
(erosional)  upon  the  basal  sandstone  member  (7a)  of  the  Onondaga. 
It  is  succeeded  by  a few  feet  of  limestone  which,  in  places,  is  much 
leached  and  very  fossiliferous.  Athyris  spirifer aides,  Delthyris  sculp- 
tilis,  Rhipidomella  penelope,  Spirifer  granulosus  and  Stropheodonta 
concava  being  very  common.  At  points  further  north  the  lower  beds 
of  the  Hamilton  consist  of  dark  colored,  impure  limestone  which 
succeeds  the  Onondaga  without  any  apparent  break.  The  characteris- 
tic fossils  of  these  layers  are  Microcyclus  discus,  Athyris  vittata, 
Eunella  attenuata,  Spirifer  fornacula,  Cano  car  dium  cuneus  and  Ony- 
chodus  sigmoides. 

The  middle  portion  of  the  Hamilton  limestone  is  dark  colored  and 
evenly  bedded,  and  contains  Ambocoelia  umhonata,  Chonetes  yandel- 
lanus,  C.  pusillus,  Cranaena  romingeri,  Parazyga  hirsuta,  Pholidops 
ohlata  and  Spirefer  pennatus.  Above  this  horizon  occurs  about  25  feet 
of  yellowish-brown,  impure  siliceous  limestone  with  few  fossils.  Near 
the  top  of  the  formation  occurs  a few  feet  of  hard,  gray  limestone 
containing  Chonetes  coronatus,  Rhipidomella  vanuxemi,  Spirifer  audac- 
ulus,  S.  pennatus,  Tropidoleptus  carinatus  and  Vitulina  pustulosa. 

Upper  Devonian — During  Upper  Devonian  time  the  Mississippian 
sea  continued  to  expand,  spreading  the  materials  of  this  formation 
more  widely  than  those  of  the  preceding.  In  the  N.  E.  % of  section 
34,  T.  II  S.,  R.  2 West,  the  lower  deposits  of  the  Upper  Devonian 
are  comfortable  upon  the  Hamilton.  There  is  here  exposed  a thick- 
ness of  33  feet  of  yellowish-brown  (black  where  unweathered),  silice- 
ous, shaly  limestone,  cherty  near  the  top,  and  marked  by  Leiorhynchus 
globuliformis,  L.  mesacostalis,  Reticularia  laevis  and  Spirifer  pennatus. 
At  other  points  this  cherty  phase  is  succeeded  by  50  or  more  feet  of 
greenish  to  black,  almost  barren  shales.  These  siliceous  and  dark 
colored  shales  are  probably  the  equivalent  of  the  calico  rock,  a mottled 
and  leached,  siliceous  shale,  present  further  south  in  Union  and  Alex- 
ander counties.  They  doubtless  correspond  with  the  Chattanooga 
black  shale,  Ohio  black  shale.  New  Albany  black  shale,  and  the  Lower 
Portage  beds  of  other  states. 

Conclusion. 

The  present  studies  have  shown  that  the  pre-Mississippian  beds 
have  a much  wider  distribution  in  southwestern  Illinois  than  was 
formerly  supposed.  They  have  distinguished  the  presence  of  a bed 
of  blue,  fossiliferous  shale  (2b  of  section)  containing  the  Cyclo- 
cystoides  and  Phylloporina  fauna,  immediately  overlying  the  Thebes 
sandstone  and  shale  horizon.  They  have  demonstrated  the  presence, 
in  this  region,  of  Silurian  beds  corresponding  with  the  Clinton  forma- 
tion in  Ohio.  They  have  shown  that  the  massive,  crystalline  lime- 
stone underlying  the  Clear  Creek  cherts  in  Jackson  and  Union  coun- 
ties, belongs  to  the  New  Scotland  formation  of  the  Helderbergian. 
They  have  demonstrated  the  Upper  Oriskany  age  of  the  Clear  Creek 


YEAR  BOOK  FOR  I907. 


[BuLU  No,  8 


I16  . 


cherts.  They  have  disclosed  the  absence  of  the  greater  portion  of  the 
Onondaga  formation  in  Alxander  county  and  in  the  southern  portion 
of  Union;  and  they  have  shown  that  the  Hamilton  forrnation,  in 
Union  county,  continues  upward  without  a break  into  the  Lower  Port- 
age beds  of  the  Upper  Devonian. 


NOTES  ON  THE  SHOAL  CREEK  LIMESTONE. 

(By  JON’XrUDDEN.) 


Contents 

'•  Paqb 

Introduction  1181 

Earlier  investigations 118 

Known  distribution 120 

Description  of  exposures 120 

Macoupin  county 120 

Madison  county 122 

Bond  county 1 122 

Clinton  county 122 

Washington  county •• 125 

Summary 125 


ii8 


YEAR  BOOK  FOR  I907. 


[BuTjL.  No.  8 


Introduction. 


A fundamental  problem  in  the  investigation  of  the  coal  fields  of 
Illinois  is  the  correct  correlation  of  the  productive  veins.  Sixteen 
different  coal  seams  were  recognized  by  the  old  geological  survey, 
and  were  grouped  in  two  divisions,  the  “Upper”  coal  measures,  includ- 
ing the  thiu  and  unproductive  coals,  and  the  “Lower”  coal  measures, 
containing  the  thick  and  productive  seams.  A limestone  formation 
supposed  to  be  more  or  less  continuous  throughout  the  coal  measure 
area  of  the  State,  and  commonly  called  Carlinville  or  Shoal  Creek 
limestone,  was  believed  to  mark  the  plane  separating  these  two  divis- 
ions. During  the  past  season,  several  weeks  were  devoted  by  the 
writer  to  an  attempt  to  trace  the  outcrops  of  this  limestone  in  the 
southwest  part  of  the  State. 

Earlier  Investigations. 

This  limestone  formation  has  been  known  under  various  names. 
In  Illinois,  Indiana  and  Kentucky,  no  less  than  six  different  local 
names  have  been  applied  to  limestones,  all  of  which  are  probably  to 
be  referred  to  this  one  horizon.  The  names  Curlew,  Shoal  Creek, 
Carthage  (?),  Carlinville,  New  Haven  and  Somerville  limestones  are 
all  believed  to  be  synonomous  for  localities  described  in  this  State. 
Observations  have  not  yet  been  carried  far  enough  to  make  this  quite 
certain. 

The  earliest  observations  on  the  limestone  under  consideration  were 
made  by  Owen,  in  Kentucky.  The  Carthage  limestone  was  noted  in 
Union  county,  Kentucky,  “one  mile  below  Uniontown.”*  Its  strati- 
graphic position  in  the  Kentucky  section f is  between  the  Kentucky 
coals  numbers  17  and  18.  It  is  described  as  having  a thickness  of 
seven  feet. 

The  Kentucky  and  Indiana  coal  fields  were  studied  earlier  than 
the  Illinois  field,  and  attempts  were  made  in  these  early  reports  to 
correlate  all  of  the  coal  horizons  with  those  of  the  Pennsylvania  fields, 
whose  sections  were  better  known.  The  first  attempt  at  correlation 
of  this  kind  was  made  by  Owen  in  his  report  on  the  Kentucky  coal 
measures,!  where  the  relation  of  the  Curlew  sandstone  and  limestone 


♦Kentucky  Geol.  Surv.,  vol.  1,  p.  60,  1856. 
tKentucky  Geol.  Surv.,  vol.  3,  p.  18.  1857. 
iKentucky  Geol.  Surv.,  vol.  3,  pp.  13-23,  1857;  vol.  4,  p.  387,  1867. 


Udden.J 


SHOAL  CREEK  LIMESTONE. 


1 19 

was  shown  graphically,  the  limestone  occurring  beneath  a heavy  ledge 
of  sandstone  and  above  a thick  conglomerate,  the  Curlew  sandstone 
being  considered  the  equivalent  of  the  Mahoning  sandstone  of  Penn- 
sylvania. ^ 

Lesquereux  in  his  Report  on  the  Distribution  of  Geological  Strata  in 
the  Coal  Measures  of  Indiana*  discusses  the  possible  occurrence  of 
the  Curlew  limestone  in  a section  at  Rockport,  Spencer  county,  Indiana. 
It  is  doubtful,  however,  if  the  limestone  in  this  section  is  the  equiva- 
lent of  the  Curlew  limestone  of  Kentucky,  since  no  thickness  equivalent 
to  that  given  in  the  section  has  ever  been  noted  at  other  nearby  localities. 
I In  Illinois  the  earlier  investigators  aimed  to  correlate  the  sections  of 
the  coal  measures  with  the  Kentucky  and  Indiana  sections.  Lesquereux 
I was  no  doubt  the  first  one  to  record  the  extensive  development  of  this 
' limestone  formation  in  Illinois,  the  Curlew  limestone  being  noted  in  a 

I section  at  Shawneetown  in  his  report  on  the  coal  fields  of  Illinois. 

He  regarded  this  bed  at  Shawneetown  as  identical  with  the  limestone 
I in  a section  near  Hollaway,  in  Henderson  county,  in  Kentucky.  In 

I the  same  report  the  author  mentions  the  following  localities  where 

I the  Curlew  limestone  was  observed,  ‘‘on  the  Kaskaskia  river,  two 

I miles  south  of  the  town  of  Carlyle”  and  “at  Jolofifs  old  mill  site,  ten 

I miles  south  of  Carlyle.” f In  Macoupin  county  the  Curlew  limestone 

was  observed  in  the  vincinity  of  Carlinville.J; 

There  seems  to  be  an  error  on  the  part  of  Lesquereux  in  the  correla- 
tion of  this  limestone.  In  Kentucky  his  so-called  Curlew  limestone  is 
not  identical  with  Owen’s  Carthage  limestone.  The  Carthage  lime- 
stone occurs  some  940  feet  higher  up  in  the  “Connected  Section  of 
Upper  and  Lower  Coal  Measures  of  Kentucky.”§  In  Macoupin  and 
Clinton  counties,  Illinois,  the  Curlew  limestone  is  the  equivalent  of 
the  Carthage  limestone. 

In  his  report  on  the  Geology  of  Washington,  Clinton  and  Jefferson 
counties,  II  Englemann  characterizes  quite  fully  the  limestone  as  it  is 
developed  in  these  counties  and  calls  it  the  Shoal  Creek  limestone, 
apparently  because  of  its  excellent  exposures  along  this  creek  in  Clinton 
county.  In  describing  the  Geology  of  Gallatin  county,^!  Cox  identified 
limestone  near  New  Haven  with  “Owens  Carthage  limestone,”  and 
in  a report  on  the  Geology  of  Bond  county,**  Broadhead  identified 
the  limestone  occurring  along  Locust  Fork  creek  as  the  Shoal  Creek 
limestone. 

In  a detailed  generalized  section  of  the  coal  measures  of  Illinoistt 
constructed  by  Worthen,  the  Shoal  creek  limestone  was  placed  between 
coals  number  9 and  'io.  Both  the  lithological  and  paleontological 
characters  were  briefly  described  and  typical  localities  at  which  the 
formation  is  best  exposed  enumerated.  In  LaSalle  county the  same 
author  referred  a limestone,  number  3 in  his  section,  of  the  river 
bluff  in  the  neighborhood  of  Peru,  to  the  Carlinville  limestone. 

♦Indiana  Geol  Reconn.  Report  1859-60,  p.  310,  1862. 
till.  Geol.  Surv.,  vol.  1,  p.  222,  1866. 
mi.  Geol.  Surv.,  vol.  1,  p.  227,  1866. 

^Kentucky  Geol.  Surv,  vol.  3,  pp.  18-23,  1857. 

mil.  Geol.  Surv.,  vol.  3.  pp.  148,  159-164,  175,  220;  1868. 

mil.  Geol.  Surv.,  vol.  6,  p.  212,  1875. 

♦♦Ill  Geol.  Surv..  vol.  6.  pp.  129  alid  133,  1875. 

ttlll.  Geol.  Surv.,  vol.  6.  p.  3,  1875. 

ttlll.  Geol.  Surv.,  vol.  7,  pp.  47  and  48.  1863. 


120 


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[Bull.  No.  8 


The  name  Somerville  has  been  used  more  recently  by  Fuller  and 
Clapp  in  the  “Patoka  Folio”*  for  a limestone  which  is  probably  the 
equivalent  of  the  Shoal  Creek  limestone. 

Known  Distribution. 

The  most  northern  point  at  which  a possible  equivalent  of  the  Shoal 
Creek  limestone  has  been  observed  is  at  LaSalle.  From  this  point  its 
outcrops  have  been  traced  to  the  southeast,  passing  into  Indiana  a little 
north  of  the  point  where  the  Wabash  river  enters  the  State,  and  to 
the  southwest,  reaching  their  westernmost  point  at  Carlinville  in 
Macoupin  county.  From  here  they  are  found  in  a belt  extending 
southeastward,  reaching  their  most  southern  extension  in  Saline 
county.  A few  more  localities  are  known  in  Gallatin  and  White 
counties. 

These  are  approximately  the  boundaries  of  the  Shoal  Creek  lime- 
stone as  mapped  by  the  former  survey.  In  the  detailed  mapping  now 
in  progress  some  minor  deviations  from  this  outline  will  no  doubt  be 
found.  Within  these  boundaries  the  limestone  when  present  lies  at 
some  distance  below  the  surface,  ranging  from  less  than  loo  down 
to  700  feet.  Exposures  are  limited  to  the  bordering  belt  and  are 
rarely  met  with,  owing  to  the  drift  cover. 

Description  of  Exposures. 

The  data  collected  in  Macoupin,  Madison,  Bond,  Clinton  and  Wash- 
ington counties,  can  best  be  presented  in  the  form  of  a descriptive  list 
of  the  localities  where  the  rock  was  noted.  (See  map,  plate  4.) 

Macoupin  county — ^1.  The  most  northern  exposure  observed  is  located  on 
the  Walker  farm  in  Macoupin  creek  in  the  northeast  quarter  of  section  35, 
T.  10  N.,  R.  VII  W.,  where  the  following  section  was  noted: 

Feet. 

3.  A chocolate  colored,  coarse  grained  limestone,  in  beds,  one  half  to 
six  inches  in  thickness.  This  limestone  has  a fauna'  abounding  in 
Producti  and  Bellerophons.  In  examining  the  fossils  the  following 
were  identified:  Productus  longispinus,  Productus  punctatus,  Pro- 
ductus  cora,  Productus  nehraskensis,  Productus  semireticulatus, 
Bellerophon  mont  fort  anus,  Bellerophon  percarinatus,  Bellerophon 
meekanus,  Aviculopecten  occidentale,  Straparollus  subquadrata, 
Chonetes  variolata,  Orthoceras  rusTiense,  Der'bya  crassa,  Spirifer 
cameratus,  Lophophyllum  proUferum,  Seminula  argentea,  8piri- 


ferina  kentuckiensis,  Myalina,  sp.  und.,  Murchisonia,  st).  und 3% 

2.  Grayish  colored  shales 10 


1.  A very  hard,  bluish  gray  limestone,  occurring  in  seams  varying  from 
3,  8 to  12  inches  in  thickness.  On  weathering  the  limestone  turns 
brown,  containing  such  fossils  as  Seminula  argentea,  Reticularia 
perplexa,  Productus  longispinus,  Hustedia  mormoni,  Pugnax  uta, 
Dielasma  hoivedens,  Amhocelia  planoconvexa,  Spirifer  kentuck- 
iensis   2 

2.  Between  three  and  a half  and  four  miles  west  of  the  last  locality,  on 
Harrington  creek  in  the  northwest  quarter  of  section  31,  T.  9 N.,  R.  VII  W., 
the  same  limestone  as  number  one  of  locality  number  one  was  observed.  Its 
thickness  is  about  6 feet,  and  on  fresh  exposure  has  a bluish  gray  color,  but 


*U.  S.  G.  S.  Geol.  Atlas  of  the  U.  S..  Patoka  Polio,  No.  105,  1904. 


stale  (teiolosical  Survey,.  Bulletin  No.  8.  Pl.  4. 


•Map  sho\viiif>:  distribution  of  Shoal  Creek  Limestone. 


Uddbn.] 


SHOAL  CREEK  LIMESTONE. 


I2I 


on  weathering  it  turns  brown.  The  beds  vary  in  thickness  from  6,  12  to  18 
inches.  Fossils  are  rather  few  in  number  and  the  most  conspicuous  form 
being  a gasteropod,  apparently  a Naticopsis,  which  is  associated  with  Spirifer 
cameratus,  Reticularia  perplexa.  Seminula  argenea,  LopUopfiyllum  pro- 
liferurriy  and  an  undetermined  pelycypod. 

3.  On  the  east  side  of  Spanish  Needles  creek,  in  the  southwest  corner  of 
the  northwest  quarter  section  21,  T 9 N.,  R.  VII  W.,  the  following  section 
was  observed: 

Feet. 

2.  A bluish  gray  limestone  very  hard,  in  beds  9,  12  and  18  inches  in 
thickness,  breaking  into  very  irregular  splintery  pieces.  It  weathers 

to  brown J 

1.  Grayish  shale  with  some  bituminous  partings 3-4 

4.  In  a small  tributary  to  Spanish  Needles  creek,  in  the  northwest  quarter 
of  section  28,  T.  9 N.,  R.  VII  W.,  limestone  and  shale  was  observed  in  the 
same  relation  as  in  locality  number  three. 

The  Shoal  Creek  limestone  can  be  traced  along  the  greater  part  of  Cahokia 
creek  from  its  headwaters  in  section  36,  T.  8 N.,  R.  VII  W.,  to  section  25, 
T.  7 N.,  R.  VII  W. 

5.  Along  the  Cahokia  creek  east  of  Mount  Glare,  close  to  the  center  of 
section  36,  T.  8 N.,  R.  VII  W.,  the  following  section  appears: 


Feet.  Inches 

4.  Dark  gray  colored  limestone,  in  beds  varying  from  6 to  18  in- 
ches in  thickness,  on  weathering  turning  brown.  This  lime- 
stone assumes  a pebbly  appearance  on  weathering,  and  this 
is  due  to  the  unequal  hardness  of  the  different  parts  of  the 
rock.  The  following  fossils  were  observed:  Reticularia  per- 
plexa, Spirit er  cameratus,  pugnax  uta,  Hustedia  mormoni, 

Seminula  argentea,  Lophophyllum  proliferum,  Productus 


longispinus,  and  an  undetermined  gasteropod 6-7 

3.  Dark  shale 1 

2.  Coaly  seam 1 10 

1.  Dark  colored  shale 4 


6.  Further  south  along  the  same  creek  in  the  southeast  quarter  of  section 
12,  T.  7 .^N.,  R.  VII  W.,  the  same  limestone  was  observed  with  a thickness 
approximately  7 feet. 

7.  In  the  northeast  quarter  of  section  13,  same  township  and  range,  along 
the  same  creek,  limestone  overlies  a shale  as  below: 


' Feet. 

2.  Grayish  colored  limestone,  with  an  abundance  of  the  corals  Lopho- 


phyllum proliferum  and  Campophyllum  torquium 5 

1.  Grayish  colored  shale 7 


8.  Another  locality  is  on  a small  tributary  to  Cahokia  creek  in  the  north- 
east quarter  of  section  19;  in  the  northwest  quarter  of  section  20,  and  in  the 
south  half  of  section  17,  T.  7 N.,  R.  VI  W.  The  thickness  of  the  limestone 
is  about  5%  feet,  dark  gray  in  color,  occurring  in  beds  6 and  12  inches  in 
thickness.  On  weathering  the  limestone  assumes  a brown  color.  A few 
fossils  were  noted,  especially  a gasteropod,  which  has  been  observed  fre- 
quently in  other  places  besides  Productus  longispinus,  Reticularia  perplexa 
and  Seminula  argentea. 

9.  About  one  and  a half  mile  west  of  Staunton,  along  the  creek  running 
north  and  south  through  the  center  of  sections  24,  25  and  26,  T.  7 N.,  R.  VII 
N.,  limestone  is  fairly  well  exposed.  In  the  southwest  quarter  of  section  30, 
T.  7 N.,  R.  VI  W.,  a quarry  has  been  worked  in  this  limestone,  and  the  follow- 
ing relations  were  observed: 


122 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


Feet. 

4.  Worthen’s  chocolate  colored  limestone.  A very  coarse-grained  lime- 
stone, in  places  resembling  a calcareous  sandstone.  It  varies  in 
color  from  yellow  to  brown.  On  weathering  this  rock  has  become 
very  porous  and  readily  disintegrates.  It  contains  numerous  fos- 
sils, such  as  different  Producti  and  a number  of  Bellerophons.  On 
account  of  the  extensive  weathering  that  the  rock  has  suffered,  the 


fossils  are  usually  poorly  preserved 3-4 

3.  Grayish  blue  shale  without  fossils 15 


2.  A bluish  gray  colored  limestone,  in  seams  varying  in  thickness  from 

9,  12,  18  and  24  inches.  On  weathering  the  limestone  turns  brown.  614 
1.  A grayish  colored  shale.  A small  seam  about  3 inches  in  thickness 
immediately  underneath  the  Shoal  Creek  limestone  was  very  fossil- 
iferous,  containing  a great  number  of  Ghonetes 4 

Madison  county — 10.  The  most  conspicuous  exposure  of  the  Shoal  Creek 
limestone  observed  in  this  county  is  to  be  found  near  the  village  of  Saline, 
on  A.  J.  Criaft’s  place,  in  the  northwest  quarter  of  section  4,  T.  4 N.,  R.  V W., 
on  Silver  creek.  The  following  section  was  noted  in  quarry  operated  by 
Mr.  Craft: 

Feet. 


4.  Light  colored  shale  calcareous 214 

3.  Dark  gray  limestone,  rather  fine-grained,  tough  and  breaking  into 
small  irregular  splinters.  Containing  fossils  such  as  Seminula 
argentea,  Pugnax  uta,  Productas  longispinus,  Spirifer  cameratus 

and  Naticopsis  altonensis 414 

2.  A small  seam  of  dark  colored  shale  that  contains  a rather  large  num- 
ber of  fossils,  especially  a Ghonetes,  Derbya  crassa  and  Productus 

longispinus  1 

1.  A black  slate,  very  stiff  and  with  a great  number  of  joints,  containing 

no  fossils 214 


11.  In  the  creek  near  the  south  line  of  the  southeast  quarter  of  section  31, 
T.  3 N.,  R.  V W.,  near  by  to  the  north  the  rock  was  formerly  quarried. 

12.  A little  to  the  west  of  the  Buckeye  school  house  in  section  20,  T.  3 N., 
R.  V W. 

13.  In  the  bed  of  the  main  creek  near  the  north  line  of  the  northeast 
quarter  of  section  19  the  limestone  is  exposed  for  a distance  of  10  rods  or 
more.  In  a ravine  joining  this  creek  from  the  south  in  the  northwest  quarter 
of  the  same  section  it  also  appears  in  a face  6 feet  high. 

14.  In  the  bed  of 'the  main  creek,  some  rods  northwest  of  the  center  of 
the  northwest  quarter  of  section  1,  T.  3 N.,  R.  VI  W.,  were  broken  blocks 
somewhat  disturbed. 

15.  About  two  miles  north  and  one  mile  west  of  Highland  the  limestone 
is  exposed  in  a creek.  It  here  overlies  a black  carbonaceous  slate. 

Bond  county. — 16.  East  of  the  center  of  section  33,  T.  4 N.,  R.  IV  W. 
undisturbed  ledges  of  limestone  overlie  some  black  slate,  under  which  is  a 
two  inch  seam  of  impure  coal.  The  ledges  appear  in  the  north  bank  of 
the  main  creek  running  from  west  to  east  through  the  section.  Disturbed 
blocks  of  the  limestone  appear  further  up  in  the  creek. 

17.  In  the  southwest  corner  of  section  34,  T.  4 N.,  R.  IV  W,  the  lower 
ledges  of  the  limestone  form  the  bed  in  the  creek  running  north  for  a dis- 
tance of  some  150  yards.  The  overlying  sandy  shales  were  seen  in  the  wagon 
road  to  the  south.  Slabs  of  black  slate  in  the  rubble  indicate  other  exposures 
further  up  the  creek.  In  the  bank  of  the  creek  near  the  bridge  in  the  center 
of  the  southwest  quarter  of  section  35,  T.  4 N.,  R.  VI  W,  the  limestone  shows 
in  ledges  of  considerable  thickness. 

Glinton  county. — In  the  ravine  running  from  west  to  east  through  the 
center  of  the  south  half  of  sections  2,  T.  3 N.,  R.  IV  W,  the  limestone  ap- 
pears in  several  places,  the  greatest  thickness  noted  is  four  feet.  About  two 
feet  of  the  underlying  black  stiff  slate  was  also  seen,  but  no  coal. 


Uddbn.] 


SHOAL  CREEK  LIMESTONE. 


123 


19.  The  same  rock  occurs  again  in  the  ravine  running  east  through  the 
northeast  quarter  of  section  11, T.  3 N.,  R.  IV  W.  In  the  west  bank  of  Shoal 
creek  at  the  ford  near  the  east  quarter  post  of  the  section  shreds  of  the 
limestone  were  seen  under  the  drift  and  overlying  some  24  feet  of  sandy 
bluish  shales,  which  has  several  bands  or  layers  with  concretion  of  iron 
carbonate.  These  are  mostly  flattened  bodies  about  two  inches  and  four 
inches  wide. 

20.  Near  the  center  of  the  north  half  of  section  14,  T.  3 N.,  R.  IV  W,  in 
the  south  bank  of  the  creek  which  runs  east,  the  following  section  was  noted: 

Ft.  In. 


6.  Limestone  2 

5.  Three  layers  of  limestone  measuring  respectively  2,  3 and  4 

inches  in  descending  order  9 

3.  Seam  of  clay  1 

2.  Limestone  2 8 

1.  Limestone  in  slabs  apparently  slightly  displaced  3 


The  ledges  at  this  place  have  a notable  dip  to  the  east  which  was  estimated 
at  no  less  than  two  feet  in  one  hundred.  The  lower  three  feet  of  the  rock 
exhibits  the  habit  noted  elsewhere  of  developing  parting  seams  at  intervals 
of  about  three  inches.  The  rock  has  been  quarried  in  a ravine  some  sixteen 
rods  to  the  northwest  of  this  exposure. 

21.  Near  the  east  line  of  section  23,  T.  3 N.,  R.  IV  W,  the  limestone 
was  noted  in  the  south  hank  of  Shoal  creek,  where  this  crosses  the  east  line 
of  the  section  about  one-third  of  a mile  north  of  the  northeast  corner  of  the 
section.  It  lies  at  an  elevation  of  about  ten  feet  above  the  bottom  of  the 
creek. 

22.  In  the  north  half  of  the  northeast  quarter  of  section  27,  T.  3 N.,  R. 
IV  W.,  the  bed  of  the  creek  running  east  exposes  the  limestone  for  a dis- 
tance of  several  rods.  There  is  a thickness  of  about  flve  feet.  The  weather- 
ing has  brought  out  the  quite  uniform  three-inch  layers  in  the  ledges,  es- 
pecially in  the  upper  ones.  The  upper  surfaces  of  these  layers  present  a 
knotty  appearance  due  to  numerous  irregular  elevations  of  an  inch  or  more, 
from  six  inches  to  a foot  wide. 

23.  One-fourth  of  a mile  north  of  the  center  of  section  26,  T.  3 N.,  R.  IV  W., 
two  feet  of  limestone  was  again  noted  in  the  same  creek  as  above. 

24.  In  the  north  bank  of  the  creek  in  the  northeast  corner  of  section  34, 
T.  3 N.,  R.  IV  W.,  the  Timmerman  quarry  is  located  and  this  limestone  has 
been  quite  extensively  worked.  The  section  is  as  follows: 

Ft.  In. 

6.  Limestone  in  three  ledges  measuring  respectively  from  above 
downward  8,  12  and  12  inches.  The  following  fossils  were 


noted:  Aviculopecten  occidentale,  Seminula  argentea  and  a 

Productus  2 8 

5.  Limestone  in  two  ledges,  upper  8 inches,  lower  12  inches 1 8 

4.  Dark  clay  shale  4 

3.  Limestone  9 

2.  Stony  or  indurated  shale  with  crystals  of  selenite  5 

1.  Bluish  gray  sandy  limestone  weathering  brown  disposed  to  ex- 
hibit on  weathering  bedding  seams  about  two  and  one-half 
inches  apart  4 3 


25.  Half  a mile  further  south,  in  a ravine  which  joins  this  creek  from 
the  south,  this  rock  has  been  quarried  for  a lime  kiln.  It  is  seen  to  overlie 
a black  slate.  This  is  in  section  35  same  township  and  range. 

26.  At  the  old  mill  site  on  the  west  bank  of  Shoal  creek  in  the  southeast 
quarter  of  section  11,  T.  2 S.,  R.  IV  W.,  the  following  section  was  noted 
above  the  water  during  a rise  in  the  creek: 


124 


YEAR  BOOK  FOR  I907, 


[Bull.  No.  8 


1 I in. 

7.  Limestone  in  one  strong  ledge  2 

6.  Blue  clay  shale  3 

5.  Limestone  3 

4.  Blue  shale  3 

3.  Limestone  with  alternating  clayey  layers  6 

2.  Blue  clay  shale  4 

1.  Limestone  2 0 


Almost  the  entire  outcrop  shows  seams  from  one-half  to  three  inches  apart. 
These  always  run  in  irregular  curves  up  and  down  corresponding  to  in- 
equalities on  the  surface  of  the  slabs  into  which  much  of  the  rock  is  broken. 
A syringoporoid  coral  was  noted  in  profusion  in  a block  in  the  masonry  of 
the  old  dam. 

27.  Near  the  southwest  corner  of  section  13,  T.  2 N.,  R.  IV  W.,  several 
feet  of  the  limestone  are  to  he  seen  in  the  bed  of  the  creek  near  the  wagon 
bridge  close  to  the  Breese  pumping  station. 

28.  One-fifth  of  a mile  west  of  the  northeast  corner  of  section  8,  T.  2 N., 
R.  V W.,  Knaus  quarry  is  located.  The  section  shown  in  the  quarry  is  as 
below: 


Ft.  In. 


5.  Marly  soft  shale  or  clay  with  many  fossils . 6 

4.  Limestone  in  three  subequal  ledges  separated  by  marly  and  fossil- 

iferous  clay  partings  2 

3.  Dark  shale  6 

2.  Bluish  gray  compact  limestone '. 5 8 

1.  Bluish  gray  shale  2 


29.  In  the  west  bank  of  Sugar  creek  in  the  southeast  quarter  of  section 
34,  T.  2 N.,  R.  V W.,  large  blocks  of  limestone  were  seen  in  several  places, 
and  a short  distance  to  the  west,  limestone  has  been  blasted  out  of  a well 
under  some  forty  feet  of  drift. 

31.  In  the  bed  of  the  creek  running  east  and  west  through  the  north  half 
of  the  northeast  quarter  of  section  27,  T.  2 N.,  R.  V W. 

32.  A quarry  has  been  worked  on  a small  scale  in  a ravine  south  of  the 
B.  & O.  S.-W.  railroad  near  the  west  line  of  section  22,  T.  2 N.,  R.  V W. 

33.  Quarries  have  been  worked  on  both  sides  of  the  main  creek  near  the 
center  of  section  21,  T.  2N.,  R.  V W. 

34.  Large  loose  blocks  of  the  Shoal  creek  limestone  lie  in  the  bed  of  the 
creek  a little  east  of  the  center  of  the  south  line  of  section  17,  T.  3 N.  R. 
IV  W. 

35.  North  of  the  wagon  bridge  over  the  main  creek  near  the  center 
of  the  northwest  quarter  of  section  9,  T.  2 N.,  R.  V W.,  the  rock  was  also 
noted. 

36.  Southwest  of  Qarlyle  about  two  miles  and  a half,  in  the  northeast 
(iuarter  of  section  35,  on  Stone  Quarry  creek,  a quarry  has  been  operated 
where  the  following  section  was  observed: 

Ft.  In. 


4.  A grayish  colored  limestone,  weathering  brown,  in  seams  3 and 
12  inches  in  thickness,  containing  a great  number  of  crinoid 

stems  3 4 

3.  Dark  colored  shale  with  crinoid  stems  and  Der'bya  crassa 6 12 

2.  Shoal  creek  limestone,  gray  color,  very  hard  and  breaking  up  into 
irregular  splinters,  in  beds  6 and  18  inches  thick,  with  a great 
abundance  of  Productus  longispinus  between  bedding  planes  6 7 

1.  A very  black  slate,  to  bottom  of  creek  3 


In  the  northwest  quarter  of  section  35  in  the  same  township  and  range 
limestone  similar  to  number  4 of  locality  36  was  observed.  Fossils  are 
more  abundant  and  a great  number  of  a Chonetes  and  a Productus  were 
noted.  The  limestone  is  more  sandy  and  a great  number  of  imbedded  fiakes 
of  mica  were  observed.  The  total  thickness  amounted  to  about  three  feet. 


Uddbn.] 


SHOAL  CREEK  LIMESTONE. 


125 


37.  In  a ravine  north  of  the  cemetery  north  of  Carlyle  in  section  18, 
T.  2 N.,  R.  II  W.,  a limestone  similar  to  the  above  is  observed  with  a thick- 
ness about  four  feet.  The  limestone  is  greatly  weathered  and  showed  the 
sandy  appearance  and  contains  flakes  of  mica.  Fossils  are  rather  abundant. 

Washington  county. — About  one  mile  north  of  Nashville  along  the  west 
side  of  the  creek  in  the  northwest  quarter  of  the  section  13,  T.  2 S.,  R.  Ill 
W.,  limestone  has  been  quarried.  It  is  approximately  four  and  a half  feet 
in  thickness,  bluish  gray  in  color,  very  hard  and  containing  Reticularia  per- 
plexa,  Productus  longispinus,  Seminula  argentea,  and  an  undetermined 
gasteropod.  Beneath  the  limestone,  a grayish  colored  shale  was  observed 
about  one  foot  in  thickness  containing  many  fossils  such  as  a ChoneteSt 
Derbya  crassa  and  Productus  longispinus. 

39.  A similar  limestone  has  been  quarried  about  two  miles  west  of  Nash- 
ville in  section  22,  T.  2 S.,  R.  Ill  W. 

40.  Along  Beaucoup  creek  quarries  have  been  worked  in  the  Shoal  creek 
limestone.  On  Mr.  Merkles’  place  in  the  southwest  quarter  of  section  34, 
T.  2 S.,  R.  II  W.,  the  following  section  wjus  noted: 

Ft.  In. 

1.  Bluish  gray  colored  limestone.  Very  hard,  breaking  into  irregu- 
lar pieces  and  weathering  brown.  The  following  fossils  were 
observed:  Productus  longispinus,  Spirifer  cameratus,  Pugnax 
uta,  Reticularia  perplexa,  Seminula  argentea  and  an  unde- 


termined gasteropod  4 5 

2.  A very  black  slate  to  bottom  of  creek 2 


In  digging  a well  at  Mr.  Wm.  Merkles’  place  it  was  observed  that  this 
slate  had  a thickness  of  four  feet,  below  which  a gray  shale  or  “soapstone” 
some  25  feet  in  thickness  is  reported. 

41.  This  same  limestone  was  observed  in  the  northeast  quarter  of  section 
34,  T.  2 S.,  R.  II  W.,  and  also  lalong  the  creek  crossing  the  east  and  west 
highway  between  section  23  and  26  same  township  and  range. 

Summary. 

In  the  exposures  that  have  been  described,  the  following  succession 
appears  above  and  below  the  Shoal  Creek  limestone 

5.  Chocolate  colored  linaestone,  4 feet. 

4.  Gray  shales,  15  feet. 

3.  Shoal  creek  limestone,  7 feet. 

2.  Gray  shales,  4 feet. 

1.  Black  slate,  6 inches  to  4 feet. 

The  topmost  limestone  (number  5)  is  coarse  grained  and  brown  in 
color.  In  some  places  it  has  the  appearance  of  a sandstone,  containing 
some  quartz  sand  and  flakes  of  mica.  Fossils  are  numerous,  but  in 
most  cases  poorly  preserved  on  account  of  its  rapid  disintegration  on 
weathering. 

The  grayish  colored  shales  (number  4)  vary  in  different  localities 
in  both  color  and  texture.  Occasionally  they  contain  bituminous 
partings.  No  fossils  have  been  observed  in  their  upper  portion,  but 
a few  have  been  noted  in  the  shale  resting  on  the  Shoal  Creek  limestone. 

The  Shoal  Creek  limestone  (number  3)  is  generally  bluish  gray,  com- 
pact, close  textured,  and  very  hard,  breaking  into  irregular  splintery 
pieces.  On  weathering  it  assumes  a rusty  color.  It  averages  about 
seven  feet  in  thickness.  There  are  two  features  that  are  characteristic 
of  this  limestone,  one  a blotchy  appearance,  and  another  its  tendency 
to  weather  into  seams  two  and  one-half  or  three  inches  in  thickness. 


126 


YEAR  BOOK  FOR  I907. 


[Bull.  No.  8 


It  is  interesting  to  note  the  relative  abundance  of  the  fossils  in  the 
Shoal  Creek  limestone.  The  fauna  of  this  limestone  excluding  the 
shaly  partings  occurring  between  the  different  beds,  is  quite  limited  in 
forms.  Only  four  fossils  are  abundant:  Productus  longispinus,  Reti- 
cularia  per  pie  xa,  Seminula  argentea  and  a gasteropod,  probably  Nati- 
copsis  altonensis,  usually  found  in  the  upper  foot  of  this  limestone  in 
a poor  state  of  preservation.  Associated  with  these  one  occasionally 
finds  Hustedia  mormoni  and  Pugnax  uta. 

On  comparing  the  fauna  of  number  5 of  the  above  section,  with  that 
of  the  Shoal  Creek  limestone,  one  is  impressed  with  the  difference 
between  the  two.  There  are  present  in  the  upper  rock  an  abundance 
of  Producti  such  as  P.  longispinus,  P.  punctatus,  P.  cora,  P.  nebras- 
kensis,  P,  semireticulatus,  and  Beller option  Meekanus,  and  with  these 
are  a number  of  Chonetes  variolata  and  Spirifer  cameratus. 

The  grayish  colored  shales  (number  2)  varies  in  thickness  from  one 
to  four  feet.  Fossils  have  been  found  in  the  upper  three  or  four  inches 
which  lie  in  contact  with  the  limestone.  There  is  usually  found  a 
great  abundance  of  Chonetes  mesoloba  and  Derbya  crassa. 

The  black  slate  (number  i)  is  cut  up  by  joints  which  are  usually 
five  or  six  inches  apart,  and  breaks  readily  into  thin  pieces  along  the 
lamination  planes.  Another  peculiarity  of  this  slate  is  that  it  contains 
some  grayish  white  traversions  resembling  fucoid  markings.  (Plate  5.) 
These  run  parallel  with  the  bedding  planes  and  are  from  an  eighth  to 
more  than  half  an  inch  in  breadth  and  run  variously  in  straight  and 
sinuous  courses  through  the  slate.  Their  forms  suggest  th^  these 
may  be  tracks  of  animals  which  inhabited  the  mud  which  formed  the 
slate. 

There  are  a number  of  small  stone  quarries  throughout  this  area, 
although  none  are  worked  on  a large  scale.  No  building  stone  is 
exported,  and  such  quarries  as  these,  merely  supply  the  local  demand 
for  building  stone  and  in  one  place  for  road  material. 


state  Geological  Survey. 


Bull.  No.  8,  PI.  5. 


Fuccidal  markings  in  black  slate  associated  with  the  Shoal  Creek  limestone. 


i- 


X\ 


UNIVERSITY  OF  ILLINOIS- URBANA 


N30 11 2088464927 A 


